I'm afraid I haven't any advice on how to make dreams more realistic, sorry. Mine are realistic enough (if weird and convoluted), but I just figure some people's dreams are, and some aren't.

Regarding the dream journal though, you don't HAVE to keep one, but I'd recommend sticking to it. I've found that I recall dreams more often the more I keep track of them...and when I lapse on keeping track of them for any extended period of time, I start to remember fewer dreams. I've read in numerous places that keeping a dream journal is a good step toward recalling one's dreams in the first place, so that's my opinion.

Maybe after you've kept the journal for a while longer, your dreams will be more realistic? I just noticed you're new to journaling, so it's a thought.