principally I'm with you on this one Adrian, though being a little webhost myself and considering this is 'just' a coffee forum I wouldn't bother. Having self-signed certificates sucks as every browser nowadays makes you jump through hoops to accept them, 'real' certificates cost money and free certificates from startssl.com only last a year. I do have to redo ~10 throughout the year and the process to do so is complicated.
The only thing where this would make sense for me is the clubroom (everybody on your WLAN or local LAN segment will be able to sniff the contents there, so can every technician in any ISP between you and the TMC server) and to protect your login data. But frankly, if you use a password on TMC that you use anywhere else, especially somewhere related to financial transactions, you're bust anyway.
If somebody steals my login and posts awkward stuff on here, I'll kindly ask site management for help
Oh and SSL *will* make the site slower to react and increase the load on the server, though I don't know if this would be significant considering the amount of traffic TMC generates (which I don't know).