People keep saying that, but they never stop to think what it would actually mean to make an option out of something.
The more options which are added, the more difficult it is to balance them properly. This is especially true for a game such as this with a completely flexible set of races and classes as the party. The amount of permutations quickly spirals into a range which makes it literally impossible to test. For proper balance, there needs to be a baseline of solid mechanics, not a bed of shifting sand.
Exactly. Example. Drink Potion = Bonus action. Thus, Rogue Fast Hands loses its main importance. Thus, Larian created Fast Hands as Extra Bonus Action. Now, Astarion can Dash 3 TIMES, as an Action, as a Bonus and as a Fast Hands Bonus. Likewise, he can attack with Main hand and offhand twice, or he can drink 2 potions in one round and heal up easily way more than anyone else. Making cleric healers less valuable and Astarion a one man wrecking crew instead of a team member.
What should be a "You can now Dash as a Bonus or drink a potion as a Bonus" has now become a majorly OP ability thus breaking all sorts of other mechanics and so it snowballs.