Blue
Ravenous Bugblatter Beast of Traal
I'm pro-ASI. This doesn't need to be in the 5e method of ASI vs. feat choice, just the general "able to reliably advance ability scores" way.
1. If you don't have accessible ways to advance your ability scores, you are locked in to the results of your rolls with no room for improvement. That party member with the higher strength will always hit more often and do more damage per hit. It's, frankly disheartening.
2. Because ability scores are static after character creation, if strongly encourages going for the highest meaningful score in your priamry abilities, which basically locks in certain race/class combonations. If dwarf doesn't give a bonus to INT but other races gives bonus INT, you'll find almost all wizard of the +2 INT races, some of the +1 INT races (because odd numbers don't help), and the no-INT-bonus races will almost never take it. Instead of any race/class combo being viable (even fi not optimal), many will become seriously sub-optimal and never get played.
3. It really cuts out character changes due to developing situations. Right now you can multiclass because of how the campaign has led your character. Make that pact to save your friends, take a few levels of warlock. Get healed and maybe find religion and take a level of cleric or paladin to represent. But if you can't help shape your ability scores to what you are doing now, that becomes a much bigger hit on the character, encouraging only planed-from-level-one advances.
All of that said, I wouldn't mind if ASIs were limited to raising an ability to +3 from where it started - you can lift weights to gain STR, train up your endurance for CON, and so forth - but it still keeps you a reflection of your base potential from when you were a neophyte, just trained and refined. (Yes, this would be an 18 cap in 5e for point buy/standard array if you didn't have racial mods - maybe it would need to be +5 (and still with a 20 cap) considering the assumptions of 5e math.)
1. If you don't have accessible ways to advance your ability scores, you are locked in to the results of your rolls with no room for improvement. That party member with the higher strength will always hit more often and do more damage per hit. It's, frankly disheartening.
2. Because ability scores are static after character creation, if strongly encourages going for the highest meaningful score in your priamry abilities, which basically locks in certain race/class combonations. If dwarf doesn't give a bonus to INT but other races gives bonus INT, you'll find almost all wizard of the +2 INT races, some of the +1 INT races (because odd numbers don't help), and the no-INT-bonus races will almost never take it. Instead of any race/class combo being viable (even fi not optimal), many will become seriously sub-optimal and never get played.
3. It really cuts out character changes due to developing situations. Right now you can multiclass because of how the campaign has led your character. Make that pact to save your friends, take a few levels of warlock. Get healed and maybe find religion and take a level of cleric or paladin to represent. But if you can't help shape your ability scores to what you are doing now, that becomes a much bigger hit on the character, encouraging only planed-from-level-one advances.
All of that said, I wouldn't mind if ASIs were limited to raising an ability to +3 from where it started - you can lift weights to gain STR, train up your endurance for CON, and so forth - but it still keeps you a reflection of your base potential from when you were a neophyte, just trained and refined. (Yes, this would be an 18 cap in 5e for point buy/standard array if you didn't have racial mods - maybe it would need to be +5 (and still with a 20 cap) considering the assumptions of 5e math.)