I'm Mike and I look after the RESLAN network.
Just to clarify a few points you've been discussing:
1. Steam should indeed work - The client should be fine, but we're looking at an issue where accessing steam via a browser may have some problems.
2. Spotify does have some issues, we've popped a workaround in place until we get a permanent solution from the firewall vendor.
We've been looking at this for a number of years, it's something that we've wanted to allow but have never had the demand from students. Stats-wise, we only had a handful of calls last year requesting XBL access (although I'm aware more people have wanted to do this, we've just never had feedback via official channels).
We have indeed approached the Gaming Society to ascertain interest regarding XBL/PSN usage. Should you wish to help strengthen the case of getting access via RESLAN, your best bet would be through the Gaming Society.
However, this isn't a guarantee that we'll allow XBL/PSN through RESLAN, our concern is providing access to academic materials and security of the network. Should giving access provide any problems relating to network integrity, it may not be allowed.