You need to watch your backside on things like this.
Its important to differentiate between cause and effect. The fact that a particular caution is lit is a symptom, its not a cause. Without engineering input its pretty difficult to ascertain if the problem is limited to to the system in question or whether you are looking at the tip of an iceberg.
The way I look at it any time a system flls over, there is an implied question mark over the power and data supplies to that system. 737 is kind of fading into the mists of time for me now, but off the top of my head:
1.) Maybe there is a faulty squad switch. If so, who knows what other systems could fail to transition to flight mode on take off, or vice versa on landing? Transponder, Pressurisation, idle floor, gear selection / warnings etc. You could find yourself with a christmas tree on lift off.
2.) Skid control valves work by releasing brake pressure. Do you really want a question mark over the condition of those valves?
Its one thing to take of with a system that has failed, where the cause has been identified and the system secured safe. Its another thing altogether to blast off with the aircraft in an indetermiante condition.
Whether the MEL applies legally or not is really a bit of a red herring imho, either way it doesn't absolve you from your general responsibility to ensure the aircraft is airworthy.
pb