Here are some of my thoughts about the 'preaching' work that never sat well with me:
1) If everyone in the world went preaching like the WTS wants people to do, who would be feeding us, educating us, maintaining the infrastructure, building our homes, making our clothes, doctoring and healing us, etc., etc., etc? It never made any sense to me that we ALL should be doing this as our primary activity.
2) Preaching activity is for the relatively healthy and young. Going door-to-door requires a physical and mental capacity that many aging as well as some special needs people just don't have. Therefore, the JWs are really only a religion for those with these abilities. This doesn't sound very Christian to me.
3) If you don't 'preach' you won't gain everlasting life, you won't survive Armageddon, and if you die before Armageddon, you risk not being resurrected. I was specifically told this as a child. Never found any of that in the Bible.
4) Rounding off the numbers for ease of illustration, if there are 7 million JWs vs 7 billion people in the world, that says each and every JW MUST speak to at least 1,000 people. I know my Dad hasn't spoken to this many people. How about the JWs you know?
5) In over 24 years, my Dad has never brought one person into the cult. (Yay!) I haven't asked him how many hours he has actually spent in 24 years, but man, those stats are bad. If you were a sales person with that kind of track record you'd have been fired long ago for being so unproductive.
6) When I was young, I was told that JWs are preaching to all the inhabited Earth. Oh Really?! How about some of those remote tribes in the Amazon? Who is preaching to those people? And what about Muslims in Morocco whom JWs have specifically been told NOT to witness to? I think I was flat out lied to.
edited to add: 7) If the 'preaching' work is all about getting people to study the Bible, then why don't JWs hand out Bibles when going door-to-door?