First of all, i think we should change our perspective, a LA7 player is not that good, potentially speaking, it's almost an average player these days, let's face it... LA7 players are too easy to find, they are not rare at all and higher LA players are the really good fishes.
To me, the real problem is not that they got stuck too fast, the problem is we are developing our players too fast! And i think that new players are low PR mostly because of that reason, even with The Best academy level, you rarely see PR5 players these days, developers made a good move with it IMO.
I am a little old as user, but there are older users here and as far as i know, players used to get training when CA>=LA and the result only turned in one thing: a huge gap between old users and new users. I don't how how it was the training formula back then (CA/LA/PR levels were established later), but there are 3 players that proves how thin can be the balance stuff: The 3 most expensive keepers in the game are CA>LA (
Pisan Dumrong-ongtrakul,
Jakapan Sripan and
Filip Constantinescu) if you scout them you will notice that their LA levels are low (4 or 5, depending each player and your scout level), now what would happen if we could improve our players at a fast rate or over his "limit"? I have a striker that were maxed in season 4, he was CA7 back then, he played +200 matches since he were maxed and his CA increased a point, that was about a month ago, what would his level be if he would keep increasing since then? He should be CA9 right now (as minimum), and his experience is far higher than many current players, he would be even more unstoppable than now, would that be fair? would new users have a chance, even if they are lucky to pull a really high LA defender? Remember that experience really does a difference here, a properly trained CA7/8 player can be as good as an unexperienced CA9/10 player. If we let players grow in 2 fronts, the gap will be higher! Think about new users too!
That said, i agree that players might improve something in daily training (training each day without an improvement sounds too weird), but it should be minimum (0.00 if training is bad, 0.01 if training is okay, 0.03 if training is good, no chance to increase skills if they are >=15 and 13 for goalkeeping skills), season last around 4 months, so each player could improve around 1.2 points just training and another 1.5 points from matches, 3 points per season wouldn't be that high, but at least would be worth to try getting okay training result and would push managers to risk something in daily training, avoiding to set light training workload a little bit, you could improve your player a little but the chance to suffer an injury would be higher for CA>=LA players (we mostly set them in light training workload when they are maxed, aren't we?).
When CA >= PR players can improve from training by PR but must get Good training result 
For now, i think it's a reasonable solution, if your phisyo is really good or your pockets are filled, but that's something indeed.
