This idea has been merged into another idea. To comment or vote on this idea, please visit JS-I-78 Functionality to restrict the range of values entered to cubes.
On excel we can force the user to put only number for example or only number between two number. Or only date, only a precise format and specific rule. It could be great (at least) to force the user to put number in cell. But in fact the best you can do is have the same feature as Excel and put one more feature concerning REGEX. It could be very great if we could force the user to enter a well writted email without format error. With regex we could check if it respect or not the good syntax for an email or something even more complex.