I keep up a delayed MT sub. Firstly because I use it to fill in missing data if I have system problems and my Sierra/IB feed data has a gap. I know I could now do this with SCMagic, but this is how I've always done it!
Secondly, it allows me to collect data for research purposes from exchanges I don't currently follow without needing to pay IB exchange fees. Again I could do some of this with SCMagic, but not everything.
Thirdly, it's a backup. Probably not much use as that since IB is so much more reliable than MT.
Overall I suspect that if I was starting out from scratch knowing what I do, I'd make do with IB/SCMagic and save a bit of cash.