Well it is good to be suspicious of too much running. You can try search Avira forum for "Defender" - more important than Hijackthislog to them. Why they dont disable during install I dont know.
There could be some politics and money involved. Several companies will uninstall S&D for example. At least Mcafee, Trend, Kaspersky if I remember correctly. S&D is very popular and while it make sense for you to have an open mind regarding what to use, X company might look at it differently. Stick to their path will be their advice and goal. Sometimes BS, other times may be wise. So always a question to be aware of.
Edited by Bambo, 09 September 2009 - 11:52 AM.