Welcome.
I think your observations are quite right. JW´s pretend always to be honest, deasent, trustworthy persons, who love all of mankind. The WTBTS, claims to be the only Christians that are interpreting the Bible correct and they claim to have the thruth. The basic for "shunning" or disf. members is the Bible. you say" It is best to stick the basic principles layed out in the bible and leave religion and watchtower doctrines alone". But is it possible to use the Bible as the basic for your philosofy? Take a look at 2:nd John verses 9-10. These verses are a few of what the society claims to bee the basic for parents to shun their children or for family members to be closed out, just becouse they have have discovered that someting is wrong with what the Soc. says.
Bugbear