I agree, and I wish it did upgrade, especially for players who play really really well especially as SI can't predict the future (look how Michu's went up by 25 points in the January fm13 update). It should be limited though, to perhaps only ever going up by a maximum of 10 or 15 points over the course of a career.
I also think that players who have loads of talent, but never use it, should have high PA's, ie. Ravel Morrison. I believe he should still have a high PA (170-180's) to reflect his talent, even though he would never reach it in the game due to his terrible hidden attributes and age. Eric Harrison himself said he was more talented than the likes of Paul Scholes and Ryan Giggs (who both had PA's of around 180). [Highlight here to see RM's PA-->154 ]
In some games, just to make them more fun, right at the beginning of a game, I'll bump up the -8's and -9's on my team to something near their max possible potential (so 150+ for -8's, and 170+ for -9's, but won't touch their hidden attributes. Then it's completely up to me to see if I can actually get these players anywhere near their PA's in-game, rather than have a glass ceiling dictated by the game.
Spoilers start here: I mean, for amazing prospects like [PA SPOILER] Memphis Depay or Marco Verratti, who both have -9 PA's, they could have repeatedly wonderful seasons, but barely grow and become world class because the game gave them a random PA of 150 something. But, if they instead started the game with a PA of 170 or 180 something, if they played terribly, they could ultimately still end up peaking at only 153 or something because of said **** performances, barely playing, and awful hidden stats etc., but at least they still have the chance to reach those extremely high PA's if they are developed right.
This is why I believe in flexible PA's, or at least higher PA's that are only attainable if players are developed properly.
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