You make a good point about the "value" of toys, particularly when most collectors on this board are not exactly planning to keep there toys mint and resell them later. While I understand there's some frustration when Hasbro re-release an old toy that was hard to get, or in limited release I wonder if that means people are just buying things because they are limited or rare. If you truly wanted a toy in the first place you shouldn't be to unhappy when it gets re-released or sold cheaper. Hasbro and TakTommy are a businesses there always going to be re-releasing old classics if they think there's money in it, or refining their toys or giving them more G1 paint jobs.
Of course it's all intensely personal what is worth what to who, on the two you mention above I'm of the complete reverse opinion, I wanted MP Grimlock and thought he was totally worth importing so I did, where as Unicrom I thought wasn't worth his $145 price tag, so I waited months till Armada died down and got him for less than half the original price. Now Grimlock has been announced as being releases by Hasbro, hopefully locally for those who didn't import him. Does that bother me? Not really I bought him then and there because I wanted him then and there and thought he looked awesome.
Hah you(we) wish!
I wonder what scale he will be too, I now prefer the Gimlock/Seeker scale as those releases have more detail and display better in my mind, however I do admit big MP's like Prime have a certain appeal too.