Each of AST's six cards has a place in the lore, and they would have to redo all the class quests from 30-50. They can't just remove them. Your other suggestion just reverts them. The seal system is tied to Astrodyne, and only benefits the AST. This is exactly how it needs to be since it is based on RNG, as unlucky draws will not hinder the party's dmg output.
Again, encounter design of FFXIV removes the meaningfulness of these abilities, which is a big reason why they have been removed. Their removal has been staggered, and I would say a big part of that is because they wanted them to be meaningful during encounters. Just look at a skill like Repose/Sleep which players have been saying to just delete if skill/button bloat is a problem. They are still here though.
The issue that remains with the card system is the fact that they just won't let go of the player's ability to mitigate the RNG. Undraw and Redraw are still skills they have to deal with an unwanted seal. This just leads to a higher APM for the AST, and the benefit isn't really all that worth the effort. The seal system really should just be you take what you get, period. Play and/or Draw should also be on the GCD. Weaving these damn abilities just makes me want to cry. Not kidding.