If you don't insulate the basement walls then some of the heat given off by the piping and the boiler is lost to the ground. There are charts somewhere that graph all this. Very confusing but the gist of it is that it is marginally better to insulate the pipes than not. Naturally it would be better to insulate the pipes and the foundation. The energy code requires basement floors to be insulated now also so if you keep the pipes bare in that case you get even more heat migration through the foundation.
I like to insulate all hydronic piping because I want as much of that heat from the boiler, into the baseboard as possible so that I can maintain a set delta t. This makes the boiler and system more efficient. Yes we're talking a few bucks not a fortune but every little bit helps.
Isn't a controlled or conditioned space better than a none conditioned space?
opinion of a Certified Green Professional (me)
Insulate your pipes for max efficiency and then tend to the space requirements by conditioning the space(basement)
Also repair air leakage to maximize the efficiency of the space. Types of Air handlers should be able to take care of the humidity(moisture) problem then insulate walls with closed cell styrene insul board if still Leary of moisture.
Thinking of heat loss in this way as "beneficial radiant heat" is crazy.