Reel-to-reel tape machines are hugely outdated these days. Justifiable reasons to use them are dwindling. Unless you are like Wouter van Veldhoven, in which case you are a tape-machine wielding musical genius.
The above 14-minute jam demonstrates four different tape recorder techniques that van Veldhoven uses to make what he calls "minimal techno". It's hard to tell exactly how it's all wired together, but what you've got are a bunch of machines working together as a massive sampler and effects machine. It's hugely impressive.
The coolest part of the whole system, is the automated relay/reverse he hacked together to get around the limitations of tape. Reversed delays are a common element in music these days, but you can't do it in real-time with tape like you can with loops and delays. It's basically impossible.
With digital delay systems, you can grab a sample and flip it instantly. With tape, you would need to cut the sample, flip it, reinsert it, and wind it back. Which in the studio, whatever, but it isn't really feasible in a live setting. Van Veldhoven creatively uses two machines to simulate the effect. Not bad for what most people would just consider a bunch of old junk.