frequent content updates, constant content delivery

This is a fundamental requirement for themepark MMOs. Not a bonus. Also don't list the same thing twice.

frequent balancing patches

Now if only people wouldn't flip their shit every time CCP tries to balance things, then we might see faster iteration times on balance patches. A level 2 goblin NPC doesn't complain it's got a nerf whereas EVE players will absolutely flip their shit when their carriers get nerfed because they've drifted into being PvE ships.

a level of polish we could only dream about

Sandbox MMOs are very hard to polish up as they require continuous fiddling to keep them going.

but theyre not stagnating, theyre just getting old

... You what? Every post-expansion slump WoW has happens because the content threadmill stagnates at the endgame of the expansion.

eve is stagnating

hurrdurr EVE is dying. Stagnation is not an EVE-specific problem, it's just way more visible with CCP being on vacation.