In my case, all rooms are cabled with a weird electrical standard that should get me 10G Ethernet (and does 2.5G without any issue). I'm not going to drill holes to pull my own fibre all around the place when I have perfectly good Ethernet connectivity.
Also, while 10G SFP+ NICs are vastly more available than Ethernet 10G ones, switches seem to be cheaper with 2.5/5/10G Ethernet ports than full on SFP+, unless you buy recycled Enterprise gear which would blow your power efficiency argument out of the water.
In my case, all rooms are cabled with a weird electrical standard that should get me 10G Ethernet (and does 2.5G without any issue). I'm not going to drill holes to pull my own fibre all around the place when I have perfectly good Ethernet connectivity.
Also, while 10G SFP+ NICs are vastly more available than Ethernet 10G ones, switches seem to be cheaper with 2.5/5/10G Ethernet ports than full on SFP+, unless you buy recycled Enterprise gear which would blow your power efficiency argument out of the water.