The problem with straw polls is that they are very much skewed by the people you choose to ask. Autodesk (and previously Alias) have for many years 'seeded' universities with free / cheap licenses, so a poll of students is bound to be biased in that direction. This is also one reason why Max is so common in the industry, despite not necessarily being the best tool out there. The other factor is that if they're mostly coders, they might not be familiar with
any art tools. But the fact is that XSI has a much lower profile in universities so I'm hardly surprised by your results.
That said, I'm well aware that XSI is not the most popular modelling tool out there. That doesn't mean it's not used by many people though, here's some relative stats based on exporter downloads:
Max: 1600 per month
Blender: 833 per month
Maya: 700 per month
XSI: 360 per month
That shows the approximate community split. So yes, XSI is the least popular of the big 4 at the moment, but it's still very far from 'hardly used'.
I think one of the best things for Ogre right now is more (and better) toolchains integrated with existing art tools. I would have supported any well thought out project along those lines - it just so happens that the one proposed was for XSI. No-one proposed a project like this for any other modelling tool - one isn't necessarily needed for Max since there's oFusion already, but there were no applications to do the same for Blender or Maya - but I would have supported them the same way if there had been. As it happens, I happen to be very fond of XSI anyway. The things proposed in this project are the exact things I would love to do, if I had the time. Which is precisely the definition of a good SoC project, provided we think the student has the capability, which in this case we do.
I think XSI is woefully overlooked by many. It is far, far more cohesive than most other tools I've used (not that I'm an advanced user of these things) and is really a joy to use. Consistent interface across the board, consistent SDK interface, ability to handle staggeringly large scenes, superb animation features, it's all there. Obviously I started off having a soft spot for it anyway since they were the first tool company to sponsor us, but the product itself has really won me over. I think everyone owes it to themselves to try it out, I think too many people assume it must be inferior to Max just because it's got a lower profile.
So - bottom line, am I trying to promote XSI? Well, maybe a little
But the most important factor is that art tool integration is good, period. If we'd had applications for each of the tools above perhaps the % usage would have mattered - since we didn't, it doesn't.
[edit]I've split this since it was going way off topic[/edit]