Well, there are a couple of open bug reports (84665/#2 and 118047/#42), and Jeff has put in quite a bit of effort to use libtiff (via Graphics::TIFF wrapper). I agree that probably very few people use TIFF images, but for them, it's apparently very important. I do have to be careful about going down the Rabbit Hole of putting far too much time and effort into this, for the return we get.
Putting in usage of Graphics::TIFF for systems with libtiff seems to be a no-brainer. I'm hoping that Jeff or someone could do something to ensure that Graphics::TIFF is available on all systems (i.e., building it on the fly). However, he doesn't seem to be interested in that sort of effort, in which case someone else might be interested in carrying the torch. The big question seems to be whether I should make some effort to use the existing TIFF code (should Graphics::TIFF not be installed), possibly removing function known to be broken. My preference would be to prereq Graphics::TIFF and just use Jeff's new code, assuming that it can be made available on all systems. If it can't, I don't think it's worth trying to do a lot of work on a pure Perl solution, unless it turns out that a major fraction of Perl installations can't install Graphics::TIFF.
I have other things to concentrate on right now, but plan to return to the TIFF issue in a month or so. I will look at what it will take to use the new Graphics::TIFF code if that library is installed, otherwise to just use the current code (rather than removing it, as Jeff suggests). At least, no one will lose current working functionality. Graphics::TIFF will not be a hard prereq unless someone comes up with a way to ensure that all Perl installations can install it.