Yes, Parker has definitely had his moments of brainlessness - in a number of directions and a number of scenarios. But remember that 1) he's all of 18-19 in this story and 2) in this path, he's learning as he goes along. Regardless of your morals, one does not turn into an evil manipulative genius overnight. The cops have had years to hone their skills. Parker, as yet, has not. Bet they made mistakes early on as well. Paul (the older cop) clearly read Parker the riot act over Ashley in this most recent episode - that's probably going to get Parker off top dead center with respect to her in the next episode.
I think that request has been made multiple times, but you see the obvious difficulties in pulling that off in anything vaguely close to real life. I suspect
Rich hasn't wanted to push that particular suspension of disbelief. Either that, or maybe Parker likes Becky's mom better. LOL Besides, if you were going to head in that direction, would you want Mrs. Vandermeer front and center, or Parker's mother? (I know what a lot of the folks here would say.)
Personally, I'm wondering how much longer Parker is going to chase Becky when he's got Jenna as "bird in the hand."