If you need to ask a question like that given the omitted context of my selectively quoted post, have you actually played d&d5e with other players and a DM? If not what about any other version?
Ooohkay. I think that you will need to explain yourself regarding what you just said.
I'm sure that you didn't
actually intend to suggest that I omitted context or selectively quoted your post. Partly because that would be in breach of the forum rules that you have agreed to abide by, and partly because anyone reading your accusation can just
just follow the link and see that I quoted your post in its entirety, with no omission or selection.
Likewise I'm sure that you didn't mean to insinuate that I've not played 5e or D&D in general. Its that whole ad hominem thing raising its ugly head again.
Unfortunately, while I'm sure that you didn't actually
intend to do any of those things, they are, in fact, what you just did.
One ninth level spell slot can only be used to cast a single spell. That spell must be selected from among the spells that the caster has prepared and the caster must decide when is the best time to burn a given slot with a spell they feel most fitting. Because the spell slot is not easy to recover it means that sometimes the caster will avoid casting a spell that could be useful just because they can if the player feels that the spell use is not warranted enough to justify consuming the slot. Sometimes that will result in a slot remaining unused at the adventuring day.
Yes? And the Enhanced Martial abilities might not get used either, whether because a situation where they would be relevant does not come up, or because they were being saved for a possible later contingency that never arose.
Having more options increases the chance that an ability will get used, but not every ability will get used every day.
The spell components limit spell casting. Verbal is not a very big limit, but both somatic and material components are limiting, especially at high level. Concentration is also a significant limit.
I mentioned Components already as something that might need to be compensated for, or equivalent weaknesses devised. I don't think that many of the spells I mentioned use concentration, but there is no particular reason not to just use concentration rules for an ongoing martial ability that warrants it.