Let me first start by saying I'm in the mindset that I'd rather record the actual instrument over MIDI, and my reasoning behind this thought is due to my ability to play many, many instruments and I have the rare accessibility to the actual instruments. My experience in MIDI also consists of composing from a MIDI database, and I haven't actually used MIDI in a conventional way partially due to my accessibility to instruments and players. However, this doesn't mean I don't appreciate the viability of MIDI. It has allowed people record instrumentation that they may not be able to play or have access to. It also makes independent musicians or solo acts create full ensemble tracks on a small budget. I did learn that creating MIDI tracks includes the sensitivity that I'm familiar with on an actual piano.
My mentor feels the same, or from what I have picked up from his opinions and the projects I've seen him work on. A project he has worked on recently used a trumpet part and the band had a trumpeter come and play. He does have MIDI keyboards and has used it in situations that I have already mentioned.