On the other hand the dude used a SHITLOAD of gear which was no longer being made. Whammy 1, Korg SDD 3K and A3, TC 2290 all come to mind. And then there are his vintage guitars.
Maybe the answer is way more simple then that? You get new toys, the old toys start gathering dust. Simple as that. I currently have some 15+ guitars and I myself notice that since I've begun to build my own new guitars the old guitars just sit around doing nothing. I've even recently sold my only Explorer for having become a dustbunny. And Edge has WAY more guitars then I do. But the principle remains the same, you can only play one of them at a time. On the plus side, he can afford to keep them all and put them in storage. So who knows what the future will bring.
Another thing, U2 is probably never going to play LAPOE ever again, it's not a song that's become a greatest hits classic, so why bring one of those Line6 guitars along on the 360 tour? And they did only start to play The Fly again on that tour while they were right in the middle of the last tour leg. So he just grabbed one of his guitars that he had with them instead of flying in the Line6.
And third explanation, and probably the most likely, it might have been just a phase for him where he thought they were cool. Just like for a while he thought Clapton Strats with Lace Sensors were cool, only to ditch them again a few years later.
