Monk fighting styles with Ki strikes are supposed to feel fluent - and they mostly do - however, finishers break this effect the way they are implemented.
a) make finishers auto-execute on last strike (no extra hand-sign animation)
b) make finishers be a fluent chain of strikes, with limited time allowed between each Ki strike (for example, 6 to 12 seconds)
c) make only successful hits count towards the combo
The combination of these 3 simple changes will mean, for example:
1) You can't enter an adventure and have light monk do water-light-water finisher. This is by design, as that kind of thing isn't in line with finishers being part of fluent Monk fighting style.
2) You can't "carry" a finisher around till you need it. Once again, the current implementation isn't consistent with fluent fighting style.
3) You have to actually hit stuff, so you can't, e.g. help a rogue disable trap. The new void-light-void is SO going to be misused otherwise... and once again, not consistent with fluent fighting style.
4) No more "losing" finisher on not enough Ki or other reasons ("losing" finisher = not fluent).
5) (a) makes finishers easier, but (b) and (c) make them harder = balance
6) You can't easily (and hence won't often) reposition for the perfect target of a finisher - finishers are a fluent part of your fighting, not something you prepare and let loose at the right time
7) You are rewarded for being able to watch closely whether you hit or not and to react/adapt fast, making combat draw you in more, require more of your attention
8) You never miss an opportunity to execute combo, you no longer have to watch the button on your hotbar toggle to some other icon only to go back because you actually lagged and your last strike never registered = more fluency
9) You actually have one less button on your hotbar now (important for monks!)
However some things need to be rebalanced to accommodate for this. For example water-light-water finisher only makes sense if used on casters. But casters stay behind, while the Monk is in the front lines. This means that range of the finisher needs to be increased. (Or it could actually work like it says it works: clear the area, hence be a stationary effect, perhaps with transparent cloud-like visual effect, that casters need to enter to make use of - I know I would on my caster.)
Also the finishers that require 3x same strike won't work with the current high cooldown on these strikes. It would feel more fluent to have lower cooldown. Ki cost already balances this, but it's also possible to, for example, increase Ki cost right after use and let it gradually decrease back to normal level over 3-6 seconds. This would allow a Monk to burn through Ki fast in order to execute a finisher very very quickly when necessary, making combat more fluent once again.