In what situation you will evolve a hatched pokemon?

If meta relevant, I keep 1 hatch until I hatch a better one then I Xfer, and only power 100%, 98% or 96%.

If not meta relevant it needs to be 100% or 98%, 96% or otherwise Xfer

It generally comes down to the rarity and meta relevance. If it's something worthless or borderline, I'll usually evolve something wild that's of high level and reasonable IVs. For something meta relevant, I'll usually find a high IV version of reasonable level and power it up; sometimes that's an egg, and I typically consider level 20 as reasonable.

The idea of hatched mons being increased in level has been put forward several times in the game's history and general consensus seems to have been it's balanced, i.e. lower level, but much more likely to have good IVs. With the advent of weather boosts however, I think it's time to re-explore the thought. Perhaps eggs themselves could be weather boosted, based on the conditions at their time of pickup, with levels to 25 and IVs to at least 12 or 13 (instead of 10).

What was the reason your topic about the ex raid system got removed? I mean, I didn't agree with your post, but it was well argumented from your side and I don't see why we can't have a discussion about it.

E.g., afaik private groups don't affect ex raid invitations and raiding more often on eligibliale raid gyms don't decrease your chances on a pass

Depends on the species. If it's something I want to max, I'd rather choose a hatched 93% than a level 35 82%. IV is everything for maxed mons.
But I agree that generally speaking hatched mons compare very unfavorably to weatherboosted catches. I already thought that powering up attackers from hatch to 30 was a waste before weather and now it's even worse. The IVs only matter for maxed pokemon anyway, for anything else you just need enough to hit break/bulkpoints.

All the time! I do not use scanner so getting high IV ones at lvl 35 is not much of an option. Any way the power up cost from lvl 20 to 30 is not that high.

Yes, the stardust cost is (usually) too high, but there are exceptions as others have mentioned.
(What I'd really like to see offered in the 'store' are special incubators that hatch mons at level 25 instead of 20...that would help some, and fit in level-wise with weather-boosted raid bosses!).