Pastor
No, if you change it you can get an argument with the people who get relegated, because you make it ten when it was two, that's really shit.
The possibility to change number of promoted/relegated could be very useful, for example my league pro tier is going to be empty and next season will be only two teams promoted from rookie, if there were four teams promoted then next season pro tier would be more challenging.
Of course you need to talk about it with all league teams before changing promotion/relegation (like every other decision).