Son of the Serpent
Pupil
Ah. Well you see...How about some examples to demonstrate your issues?
I disagree with your entire post - there's nothing seriously wrong with how actions work in 5e.
That doesn't means it's perfect; bonus actions sometimes cause me to scratch my head - they're not elegant but they do the job.
By the way, D&D spellcasters being able to combo spells sounds like a recipe to FUBAR the game royally. What an incredibly bad idea. Plus, it won't be so great when enemy spellcasters do that to you:
'And the enemy mage combos a 10d6 fireball and Power Word Kill. He's a sorcerer so let's spend some sorcery points to heighten the damage.'
All i see here is a positive?
I like the chances of death to be high?
Letting the classes with the most inherently broad attack options be creative is a good thing?
Hard is good? (I say that as a current player and not dm in 5e)