I've never owned Thiel's and I am a little surprised to hear what you said given the extensive cross-over design they use--why go cheap on the wires? It does make a big difference as to which driver you are talking about. The tweeter may have what appears to be wimpy wire, but actually could be a very pure copper or silver that is well suited to the task. On the other hand, the woofer, will draw a much larger load and should have beefier wire. If it doesn't you could always fix that yourself, but be cautious as many designers figure in the wire (resistance) as part of the cross-over (network) design. I have no idea what Thiel's intentions are.
Internal Speaker Wiring ??
I just had occasion to pull a driver from my Thiel 7's and was quite surprised to see what looked like a rather "wimpy" wire connecting the driver to the crossover. It made me wonder if the "weakest link" theory applied to internal speaker wiring. In other words, am I foolish to spend hundreds of dollars on amp wiring and speaker cable when there may only be garden variety wiring inside the speaker ??