Hey Mad, this is a good topic. I never really considered it before but what your saying I agree with. When Jesus got baptized, other than John who else was there besides the two of them? I can't recall but is there any biblicle record of His disciples getting baptized? If so, what were the circumstances? The Ethiopian Eunuch that got baptized, if I recall correctly only Phillip and maybe the Eunuch's attendant or attendants were there right? At Pentecost a few thousand got baptized, but that was a major event with a purpose behind it that had nothing to do with people doing it publically for the sake of having witnesses.
The only reason I could see other than what you've stated already Mad, is maybe the convenience of doing it at an assembly or a convention. Plus being that we have conventions and assemblies every so many months, maybe it gives studies time to think things over before taking that dip. Me personally, I'm a private person, and have never been fond of assemblies, conventions, and lately I'm disgusted at meetings. If I had the chance of doing it over I would rather have my baptism be a private, solemn affair. The same as my prayers.
I guess what else can we expect from a religion that is all about appearances. This religion under Rutherford had the sole purpose of irritating people for publicity, and since then its been an organization thats all about patting itself on the back, criticizing any other belief systems, and worshipping the GB. To choose worship in a quiet, dignifying manner would bring suspicion upon that individual. You can't leave the religion quietly, the same as you can't join quietly. Its like a prison gang almost. Blood in, blood out.