For many, it is probably for aesthetic reasons; for some people, it also depended on what the electrician preferred (wanted to sell). I can definitely recommend thinking beforehand about which (wireless) dimmers, roller shutter switches, thermostats, etc. are needed and then checking if there is a solution in the program. Sockets, (normal) switches, push-buttons, etc. are usually not the problem. Especially with LED dimmers, it was still difficult a few years ago. I cannot say whether there is much of a price difference. For the meter cabinet, definitely Hager and at least 3 fields, meaning 105 cm wide. RCDs and circuit breakers as well...