Its not black and white with this issue, tons of grey area. Some people use computers all day for personal and professional business and do not want to sit in front of a computer to have fun making music. The newness of using a standalone drum machine will be inspiring and motivating in the beginning but there is no way to tell if in the long term your familiarity with software will spoil your desire to put in the extra work necessary to consistently use an MPC to make your tracks. Its inspiring to work in different ways, so never discount that.
Maybe instead of investing in an old drum machine you can give yourself a chance to get more hands on with you production, buy a mic+ a real Hi Hat, and some percussion and incorporate that into your work flow. The more live instrumentation you can work with, the less mousing you will have to do during your initial creative process because it will just be about recording. This leaves the computer for editing and precision related tasks, which the computer does very well.
Just a suggestion, I know the MPC looks cool and all but there are other ways to inspire your production, most likely if you get an MPC you are just going to try to learn how to do the same things you are already doing now, but just with the MPC....which is a disaster waiting to happen. Inspiration should also facilitate growth