I'm not a roll-under fan in general, but when I saw the TIH rule, it seemed like such a kludge to me.
Little history on the TIH rule...
Back in the late 90's, I was running a MT Traveller game, when T4 hit the shops. We migrated over to the new rules.
It wasn't long before me and my group found a lot of problems with the T4 task system. I was active on the TML at the time, and I posted a couple of fixes (one of which is still fairly popular with T4 gamers--it's called KB2.0, and you can get it on Freelance Traveller).
Marc was popping in and out of the TML around that time, and we had a massive flame war going on about T4's task system. There are always those who will stick by a published work simply because its published and seems "official", regardless of the quality.
Then there are those (my side of the fence) who will call a spade a spade, bitch about how broke it is--when it ain't supposta be broke--and try to fix it (KBv2.0).
Somebody on the TML (not me), as a direct result to this T4 task system flame war came up with the TIH rule as a House Rule fix. One of these days, I'd like to back over the archive and see who that was, because I've forgotten.
Anyway, it was this TML poster, not Marc, who came up with the TIH rule (originally, it was call the IHTIT rule, for "It's Harder Than I Thought").
It was that House Rule that seem to quench the flames of the T4 task debate. Even I couldn't argue with it. Sure, you're right, it was a band aid slapped onto the T4 system, but as for pluggin' the dike, it worked quite well with little fuss.
Marc was also fussing with the T4 task system at the time as well. People bitched about the half die (the D3's of the original T4 task system), and he removed those when he published the T4.1 task system that is seen on Marc's T4 Gamemaster Screen.
Since that time, Marc has adopted the IHTIT rule, changing the name to the TIH rule (for "This Is Hard!").
And, that, ladies and gents, is how the TIH rule made it into the official T5 game...