For years Telus has been saying that they have a superior network, however, the network might now have fallen behind the times and they need to do this to match the speeds Shaw offers. If the network has gotten into such a bad state that's a big concern for the future and people may have to start considering going to *gulp* Shaw. I have no idea why Telus would do this, the only thing that matters though is if they'll enforce the bandwidth caps
I think there are two main reasons they did this:
1) To match what Shaw offers. That way if the Telus network IS in bad shape and they need more bandwidth on the backbone they can easily start enforcing the caps which should then free up excess backbone for the network. (I mean through everyone using less overall, I realize this isn't a good technical explanation) Do I think the Telus network is in this bad of shape? Not really, but only their network engineers and excs know for sure. As an FYI Shaw offers 250gb for 25mbps and 400gb for 50mbps:
* As an aside, these bandwidth caps will become important in the future so why Telus doesn't keep them high and use that as a competitive advantage I don't know. If they do have the better network they should start advertising the higher caps and cause Shaw to match, which if they have a bad network should cause their network performance more problems, thereby making Telus look good. I think Telus is going the way of Telus Mobility though and looking to gain less customers with a higher ARPU (Average Revenue Per User).
2) I think that Telus, along with other ISPs is hoping the the UN finally decides they should attempt to govern the Internet along with the ITU and start charging for the Internet the way that phone calls are charged between countries. (There's formerly secret negotiations going on now.) Would this be bad for everyone but the ISPs? Yes. However, it would allow ISP's to start charging extra tariff's for bandwidth and thereby realize a new revenue stream that is currently dormant. We should all hope this doesn't happen. Anyway, if it does then Telus would love the lower bandwidth levels as they'd have a large new revenue stream that would expand exponentially as more video is transmitted online.