How would you improve it then?
Why have speechcraft and mercantile skill,only for them to be bypassed by creating an illusion/charm spell for two seconds.
Well, A) they've addressed that specific issue now that conversations are realtime and B) by removing the ability to set the duration of charm spells. Instead of destroying the entire system, you just remove one particular part of it that breaks things.
Most of the problems with specific spell effects could be resolved by changing the mechanics of that spell effect slightly. Constant effect enchantments could still have a charge that drains over time (which would limit abuse of chameleon, invisibility, and so on). Chameleon's duration could vary based on movement and action. Summons could be soulless -- for that matter, you could use a soulgem as a required component for summoning, such that if the spell expires, the gem is fine, if the creature dies, the gem shatters. It would mean that they wouldn't need a billion different summons, just one, where the magnitude indicates the power of soul that can be made brought forth from its gem to serve.
Basically, it seems like they're choosing flashy (and, hopefully, balanced) over choice and customization and maybe a little goofiness as a result. Unlike losing skills, which is basically just a name and number in a spreadsheet, taking away mechanics definitely impacts the player experience.
I hope that the CK lets us make spells. We can at least design some custom spells that way. Still, it's definitely a regression in capabilities, and that's a shame.