There is too much of that due to the overly narrow parameters they set for themselves - no adventuring spells for instance. There are Abilities and Spells that are very much not useless at all within those parameters tho. The weapon Modals are massively annoying, but evidently
Haplo who knows more than anyone says some are good?
The STR/INT whining is just straight up ghey.
The -25 defense debuff modals (club-Willpower, flail-Reflex, morningstar-Fortitude) are extremly good as far as party synergies go. Morningstar modal can actually be beneficial even personal damage output wise, particularly on a Barbarian with Brute Force (targets Fortitude instead of Deflection if lower) or possibly a specialized Fighter using a lot of Clear Out (aoe!) and Mule Kick (these target Fortitude directly).
Particularly the morningstar modal makes landing destructive stuff like Disintegrate, Death Ray and many others banal (and crits likely). Club is very useful to support early Ciphers, before they can get stellar accuracy vs Willpower and before Wizards get Miasma and such.
Axe Bleeding Cuts modal is extremely potent, it melts even megabosses after a few applications. It does slow you down a lot... but maybe you'll apply it semi-passively - for example as Ripostes/Retaliations. And maybe you'll spam Forbidden Fist while holding an axe and will create chains of axe swings via Swift Flurry/Heartbeat Drumming (probably needs Community Patch to work).
Rapier with its +20 Accuracy modal is barely slower then a "normal" speed weapon (like saber), while making you crit like crazy.
Single Pistol with modal is slightly faster then dual-wielding, barely less accurate and gets a 20% crit conversion.
+20 Accuracy on Arquebusses is great for alpha striking before reloading - even better from Stealth, as 1st reload/recovery from stealth is accelerated.
Same deal with Rod with its large aoe blast - you can attack twice exiting stealth (with Bounces and good chances for proccing Ondra's Wrath aoe, if using Tekehu's rod)- and maybe re-hide to get fast recovery again.
Arquebus (Prone) and Crossbow (Interrupt) modals are great to chain interrupt dangerous enemies - particularly shine in megaboss battles.
Large Shield modal makes you way sturdier vs ranged attacks/spell like abilities. Particularly nice for boarding ship barrages.
Blunderbuss Powder Burns are clutch for triggering Streetfighter special abilities effortlessly.
Increased Pen/Reduced enemy AR can be crucial to beat some enemies if you under-penetrate. However I try to avoid being in such a situation in the first place trough buffing/use of appropriate weaponry. And if you have such issues, direct RAW damage weapons might be a more reliable solution.