Really, no one has any business looking at anything I do on the Internet. I don't use Tor for everything but I may use it when I'm connecting via a network that I believe to be hostile (i.e. just about everything outside of my house)
Which ISP do you use? I would be surprised if a trustworthy ISP exists.
When they're completely consumed by their new owners, TPG, then no, there won't be a trustworthy ISP in Australia. I have high hopes for SkyMesh, though.
Using TOR for everything helps to build plausible deniability, if you are always on TOR then an external watcher can't determine if you are doing good or bad stuff.
Of course good and bad are relative terms, if your country doesn't have free speech obviously the "bad stuff" is just speaking freely
Edit:
> I'm having a hard time seeing what the compensating advantage is. How does not accepting Tor traffic to our "normal" sites lessen the anonymity of Tor traffic to sites where it is important?
The anonymity of Tor depends upon diversity. The more people using Tor for more things, the harder it is to correlate any particular person's traffic.
That being said, it is your website, and if you decide to block Tor you have as much right as your users do to use Tor. But I'd ask you to think about whether you are actually attaining any benefit.
Some background - we run several SaaS services for schools, which are politically and socially non-sensitive. The only realistic reasons anyone would want to connect anonymously would be nefarious. Allowing Tor traffic is like a bank having a special ATM round the back with no security cameras - you're giving a free pass to attackers to try anything they want with impunity.
I'm having a hard time seeing what the compensating advantage is. How does not accepting Tor traffic to our "normal" sites lessen the anonymity of Tor traffic to sites where it is important?