Currently there are a couple of long discussions going on about why current pet collecting achievements and their rewards should or shot not be retired, removed, and/or turned into Feats of Strength.
Both sides of the coin make good and valid points, and I'm still in the process of determining where I stand in this matter. What my opinion is might not make much of a difference or change anything, but I find that it's still important for me to chime in with my two cents.
If the quality of this opinion write up isn't as high, my apologies. This is a tough topic, and my thoughts on the matter are still evolving. I'm also less than well-rested, but I feel THAT compelled to write about this. ;P
Currently there are 5 pet collecting achievement rewards - 50, 70, 100, 125 and finally 150. The last three are the most recent additions to the collecting achievement tier. Two more will be joining them in MoP - 250 and 400 collected pets. Note that all of these achievements will require uniquely collected pets in MoP, and duplicates will not count.
The main topic at hand is whether or not Blizzard should remove the lower tier achievements because of the influx of 200+ new pets in MoP. Many feel that this introduction of a massive number of "easily" obtainable companions will make the current pet collecting achievements too easy and devalue the rewards and effort of players that earned them the old fashioned way and prior to Pet Battles.
There are other suggestions such as awarding those that have reached 150+ pets prior to the expansion with a FoS to recognize and acknowledge all the hard work put into their collections.
Another idea is that the achievements should not take into consideration the new capturable pets, and only pets that are collected through traditional means (vendored, dropped, quested, etc.) should count.
While I'm torn about the last two suggestions, I'm feeling somewhat strongly that the achievements and their corresponding rewards should NOT be removed. I may change my thoughts about this in the future, but after reading through the discussion threads and contemplating this notion, I'm fairly confident that removing anything will do more harm than good.
I definitely can understand the desire to maintain a sense of pride in one's accomplishments and milestones. It's never easy to accept the feeling that a task that took so long and so much effort to complete is suddenly made a common day occurrence. This is simply a product of time and the effects of going forward rather than standing still, though.
Any time new content is added, we will run into this conflict. It would be an ideal world if everyone could be seen as special for what they've accomplished and be recognized immensely for it, and all those that came after would have to undergo the exact same process to reach the same point as those that came before, but this is just not realistic.
It would require the game to be static and less dynamic with fewer changes. What kind of new content could we expect then? Not much. We simply cannot have our cake and eat it too.
So yes, things might be "easier" and things previously earned might also be earned by more people. That's progress, though, isn't it? Without this pattern, we couldn't have new shiny things added into our game world. Besides, "easy" is relative and new players or people who are only just taking up the activity may not view it the same way. How they experience it should not impact your own previous experiences, as the memories of your achievements will not be changed or erased away due to someone else experiencing a slightly different version.
To Put It Simply: Removing Things Unnecessarily Is Bad
But ultimately, this drives the fear of "what I've done won't matter anymore", and some will want some sort of compensation. I'm not against this completely, and if offered some sort of honorary badge for completing X, Y and Z, I would probably take it. There's no shame in this.
However, the idea that the compensation should deprive others of a chance at also completing and being rewarded for the same achievement is not acceptable in my eyes. It's a quick "fix" that although would appease some veteran players, it would piss off newer ones and cause a rift of "haves" and "have nots" between people.
Plus, whenever the game physically takes away an item, an achievement, etc., the outcome is almost always worse than when things are simply updated and additions are included. No one likes having things taken away from them, so why use this method to maintain a small sense of pride? It sounds more like punishment than inclusion, and isn't inclusion a large factor of this game? Including your friends and family and acquaintances to partake in activities that you might also enjoy. I mean, that's the whole idea behind the "multi-player" concept, right?
Put the shoe on the other foot, and it's a less than desirable position - to see others being able to reach and grab something that you can't, simply because it's just no longer possible. And not because the content has rendered it impossible, but because others have deemed it to be unreachable for the sake of maintaining a sense of superiority and accomplishment.
In the end, simply adding new achievements on top of what we currently have seems like the lesser of many evils. Some may perceive this as an insult to their efforts, but is it really? Is the intent of Blizzard to devalue older players' achievements and accomplishments? I don't think so, and if it is, then we are all paying the wrong company to create this game.
There might be other ideas on better ways to handle the balancing of old with new and how to maintain a fair and enjoyable experience for all. At the moment, though, what Blizzard has set up for collecting achievements appears to be the "best" way.
Like I mentioned earlier, both sides make good arguments. I can understand and relate to both, but on the grander scale of things, the community has usually bounced back much faster and better when things were added and not when things are taken away.
When was the last time someone made a negative reference to when the 75 and 100 achievements and their rewards were released? Compare that to when Blizzard removed the proto-drake achievement mounts in WotLK, and the mount situation is almost always brought up in a negative light.
Generally speaking, over time the changes and the "ease" of things becomes more acceptable since there will be higher standards to strive for. Everyone will have their chance to stand in the spotlight in some way, shape or form.