Regardless of the security of IPMI its firewalled off from almost everything. And Dell DRAC has their own security holes now, not unique to Supermicro.
I dont either, but when its needed its well worth it. Error booting? Two seconds to log into IPMI vs going and plugging in a monitor, which for me is even more of a pain since all my monitors are on desk arms. Want to reinstall an OS? Mount an ISO remotely, or even use a USB and not have to move the monitor. Want to check temperatures? Easy.
Multi port NICs are cheap, but factor that into the cost of a consumer board and that removes some of the cost savings. Plus in my case I have quad on board NICs and the single PCI-E slot is used by an Intel 10Gb SFP+ card. So then a cheaper motherboard would need two PCI-E slots, different case....
ECC is cheap enough to be good to have and this box will soon have ZFS on it. ECC isnt required but close enough to nice to have to not be a fetish item.
And with this board the CPU was included in the cost. Consumer boards generally not. So really at least for my setup, consumer boards are no savings and only more of a pain in the rear.