This is really a different topic, but as I see it cyclic initiative is the alternative to rolling new initiative each round.
That was something we just did back in time without questioning its value. Once we switched over to cyclic initiative, we never looked back: soo much faster and easier. And in games where a single attack seldom has a decisive effect (like D&D), it was strictly an improvement.
What you suggest is something I'd say can still be done with both systems.
Ergo, I would say cyclic initiative is (still) the a good thing about 5E and every other game that employs it
Your observation, however; that it's only the declaration phase that needs to be done in order, while the execution phase can be done concurrently, is certainly something I will take under consideration.
I don't read you to be saying we need to go back to non-cyclic initiative, where initiative is rerolled each round, with all that extra administration. Thank you