Funny this came up... I got my 200-day reward today.... and I've pondered going lifetime...
But there are a few reasons, one big, why I won't:
#1 (big reason). I feel like if I spend $300, Cryptic's commitment to improving the game could falter. They would have a good chunk of my money, and I'd have no written contract from them stating that new content would be developed, and existing problems would be resolved. There is also a possibility that this MMO might one day become free-to-play (face it, any MMO outside of WoW faces that prospect), and I'd have thrown that money away.
#2. There is little incentive to spend this large amount of money. A "Captain's Lounge" with characters from the show is not only very "illogical", but it also holds very little interest to me. Having a special forum avatar, and a special title is completely meaningless to me. Now... if I were to get C-Store items for free or at a significant discount (like 80% or more), or there were special quests or planets I could visit, I'd be much more inclined to go Life-time.
#3. I don't know if I'll play STO for the rest of my life. The game is fun enough to have kept my interest to get level up a Vice Admiral and a Lieutenant General, but honestly, if another space MMO came along, or even a really good Star Trek RPG, I might stop playing.
So, yeah, seeing complaints about lifetime sub value isn't a surprise to me.