I'd be happy to change a bit from the "beast-tribe" summonings mandatory trials.

Knowing where we will go in 5.0 should help. Because if we really go to Garlemald, there are less chances that we will meet primals. I would enjoy a fight against a major antagonist in the form of a trial (like Nidhogg for instance, or the Chrysalis with today's trial standards).

Raid-wise it's the same. Alexander and Omega where pretty well introduced in their respective expansions. I'd like raids brought closer to MSQ, see a real implication for what I do in side content in the world. The pattern of content in separate bubbles is certainly useful from a practical point of view but it sacrifices a lot of immersion.