And how long has it been since you hit the wrong button in a combo by mistake? A year? Three years? Let's leave out events that are less about your personal difficulty than whether your cat decided to jump on your desk.
And how long did it take you since adding a button to your rotation to make no mistakes in regard to pressing the newly extended combo correctly every time? At most an hour? And maybe five minutes more the next time you played?
Those fail checks are absolutely inconsequential to anyone beyond the bottom 25%, if not the bottom 10, and if the ability to accidentally hit one button over is all that separates you from them (1) you can still hit the wrong button just as easily as before, just on a more distinct ability, and (2) you probably shouldn't consider yourself an authority on difficulty.
Again, I probably wouldn't use the consolidation myself except on a few skills, because it's honestly easier to have my fingers trace out the timing for me. I know precisely when my Higanbana is going to need to be refreshed not because of the target debuffs but because my fingers have made n laps around my combos. But, I'm not going to insist that others don't even have the option of saving some button-space just so I can continue making the game easier for myself in that fashion.
There is literally only two fears here worth considering: that there will eventually be no space for the difficulty-free yet nonetheless enjoyable "rhythm of keys", having taken up its space instead with too many varied tactical tools, and that those new means of skill-gap may make the game too hard for a number of players (at least unless coupled with in-game support such as better ways of teaching how to actually play well). If the prior is your position, I understand it, but do not try to convince me that the system as it stands protects difficulty or skill-gap. It doesn't. It quite frankly makes the experience easier for anyone who's spent any time on their jobs.