I am not sure why there are some issues with Paul, other than some of his doctrine teaching being very cutomized to his audience of the time.
At its core, it is based on Love, Hope and Faith in Jesus Christ as our Saviour and sole mediator between us and God.
Sure he has some issues with women, widows, concerns about devote people marrying and such, which is typical of someone that viewed the end of times as close at hand. and someone brought up with strict teeachings and such.
I agree that if one was to focus on the spiritual elements of Paul's teachings, there would be less "issues" with Christianity, but at the same time Paul makes it clear ( or resanably so) how vital a personal relationship is with God through Jesus, how crucial Love is and how eternal God and Jesus's love for us is.