Actually, you can do SH or XH UQs with 10* gear just fine as long as you;
A) Most importantly, know what to do and when to do it, using the correct PAs etc. If your getting constantly K/Od then perhaps it's time to play a lower difficulty until you've adjusted, either by gear or by practice and usually, it's practice thats the problem for most people.
B) You skill tree is responsibly spec'd for your class. Far too many perfect guides, elitist skill trees and cookie cutter builds, worse are the players that 'insist' you 'must' use a specific build to be viable, whilst I'll agree that your skill points are very important - this level of perfection is unwarranted, and has been a constant source of noxious elements on the JP server.
C) Your mag is fed properly for your class, making pure mags isn't that hard and will help immensely. Tech and Ranged mags are especially easy to make, Melee is slightly more complicated but still - not really hard at all.
9/10 times a SH UQ fails like, for example Luther is because people don't know the fight, don't know the weak points. Each raid boss all have specific phases and specific attacks, sometimes knowing when to pull back and prepare for a big attack rather than going full on attack is the wise action.
The problem is that so many people, like myself that played on the JP servers know the fights, know how to react and unfortunately more than a few have become jaded and even bordering on elitist with these fights, that some players have become downright hostile against new players who haven't played PUSO before.
So instead of saying Don't join SH or XH UQ content isn't helping anyone, it's better to say is your skill level ready for higher level content? Can you effectively dodge? Can you attack weakpoints effectively? Gear helps tremendously, but the entry gear for these UQs isn't as high as your making it out to be, sure if everyone in the raid had +35 Nemesis and BIS perfectly slotted units...you could probably beat the boss in 2 minutes but then, if you had everything BIS why would you be doing the current raid UQs anyway?
Right now, content wise we're in total easy-mode, I think people need to relax a little and be constructive, help out new players - show them the tricks, if you've got explanation symbol art for Magatsu for example, share it - trust me, it'll help and people learn quickly and if someone isn't geared, then fight a little harder to pick up the slack for them as I'm sure they'll appreciate it.