Is there any point to infantry other than cheap garrison units?

[Neophyte]

Also to add: if you capture a ship in the middle of the enemy fleet it's likely they'll target and blow it up before you can get it out of there. 

Which is sad for your tech and salvage hopes but funny as hell for me as a player!

[serger]

It's also very useful to chase and board large, slow and rather expensive non-combat ships like gate-builders, terraformers and even cryotransports (colony ships).

[Panpiper (OP)]

It's also very useful to chase and board large, slow and rather expensive non-combat ships like gate-builders, terraformers and even cryotransports (colony ships).

Hmm... Now THAT might indeed be a reason to have a dedicated transport for boarding marines.

[Steve Walmsley]

To be honest I don't think the AI ever board you...

You might be in for a surprise