Agreed. These are all valid reasons why the vision game (not just stealth) is currently lackluster.
But let's talk about possible solutions:
What about introducing more advanced, legendary, mythic items that interact with stealth or invisibility in some way?
Notice how there is yet to be a support who can stealth her allies even though the design space is obvious.
Maybe Wards could occupy the trinket slot (overriding the ability to use your trinket) until they're placed, thus clearing up inventory space.
Maybe introducing more unique wards with their own pros and cons would make wards less of a gold sink and more of a supplemental defensive option (i.e. keeping tabs on your jungle and possible gank paths).
Consider how the Snitch (my rebranded mandrake ward), Sentry, and Beholder would deter / make ganks difficult for Evelynn and other stealth champs.
Maybe more ways of gaining / denying vision through champion abilities and trinkets would take the pressure off of needing Pink Wards to gain / deny vision.
Maybe more forms of pseudo-stealth (like nearsight) would make Pink Wards less optimal in certain situations, as by their nature they don't offer anything against nearsight.
See what I'm getting at? Tons of possibilities, Riot just isn't doing anything. ;c