The role of the programmer in recording production
In the parallel universe of sequenced music then the rehearsal stage takes quite a different form to band recording.
It isn't sensible at the highest professional level to record a band in anything other than a proper studio, but it is perfectly viable to sequence tracks at home and then take all your MIDI and computer equipment into the studio and transfer your work onto tape.
Although there is something to be said for experiencing great sound on big studio monitors while you are programming, it isn't really cost effective to do this when you can work for free with no time pressure in the privacy of your own home studio. In sequenced music it is far more common for the writer/musician to be his or her own engineer and producer all at the same time, at least at the programming stage, and then continue to produce in a commercial studio while a specialist engineer handles the faders.
In band recording there is always the difficulty of recognising when something is 'good enough', which is an important part of the producer's skill. In sequenced recording, 'perfection' is easily attainable and the producer's skill is more biased towards understanding the infinite subtleties of precisely what the club-going and record buying public would like this week, next week and the week after.
The art of programming consists of the selection and processing of loops (which will require copyright clearance) or the creation from scratch of a 'groove'. The importance of the groove in dance music cannot be underestimated.
There are plenty of people who don't really understand the style who watch TV music shows (they don't go to clubs, which is why they don't understand) and say, "I could write a song like that". Maybe they could, but could they invent the groove to go with it? Created a groove is easy, creating a groove that sells is not. Perhaps the producer will be a programmer in his own right, or perhaps he will guide and direct a programmer to come up with the foundation that will support the song.
In many cases, MIDI equipment is used not for dance music, but to create music which superficially sounds like it is being played by conventional instruments. The programmer's skill will be applied towards making or selecting the right sounds, not necessarily exact imitations of real instruments, and the producer will have the final say on which sounds are used. Again, much of this work can be done in a home studio and only transferred to a commercial studio at a late stage.
Finally, whether your style of music is sequenced or played live, the process of pre-production is a process of trial and error. Where people come up with ideas, try them out, and then the producer selects the best of the bunch that will pass from the rehearsal room into the studio. The next step is to put together the team that will turn a song and a collection of production ideas into a recording.