Generally, this is true, but Uge Warbands have some nice things to work with which mitigate the threat. You will almost always outnumber double and there are lots of grots to negate kills. Even an enemy with +1 for Inspiring and +2 for BMs is a long way from a solid win.

Also, barring substantial threats from template weapons, there are so many models that the Orks can bunch up and still control large swaths of the board. That limits both the angles of approach for clipping and the ability to catch small portions of the target formation.

Finally, of course, there are many Nobz and +2 Mob Up so keeping BMs on the Warbands between turns is difficult. All prep has to be done during the turn.

Clipping is still a threat. I just think "horribly vulnerable" is an exaggeration.

Personally, I like to have the equivalent of about 6-8 warbands available to choose from. A normal 3K army for me would have 3-5 warbands. You'll want extras to add boyz/grotz or Nobz to things like Landa Warbands, so that's equal to another warband worth of troops. And, of course, you'll probably want to play the occasional larger game.

As an example, I might have a Big Warband on foot, a Warband in wagonz, a warband + 2 Boyz/Grotz in a Landa, and a Big or Uge Gunz formation with added Nobz. That's a little over 1500 points and would require 5 warbands worth of nobz/boyz/grotz.