I think you will find that there is no one perfect shelter solution for every situation.
With all things UL, it is about trade offs.
Yes, the bivy and tarp that I use gives me a lot of flexibiilty and a different way to experience sleeping outdoors.
Think it would be hard to argue about a free standing tent's advantages above treeline over a tarp and bivy in bad weather.
To me, UL is about hyper speciallization....I have the gear/tools to carry exactly the combination of gear that I think is necessary for the trip at hand. The hyperspeicalization of going UL might give me a smaller margin of error if the weather turns bad or if it rains, but I am making those decisions for myself...risk vs. reward of a lighter pack.
That said, I have weathers a pretty nasty storm on Mt. Whitney above treeline that put everyone's shelters to the test and my MLD poncho tarp stood strong the whole night, where other tents had rain flys ripped off. (All about having huge piles of rock on your stakes and a tight pitch on your tarp).
Anyway, my two cents on the topic....not better, just different.