I've left a few trees in many plots over the year. It gets to be a little bit of a pain working around them and your plot won't do as well in that micro area, but, assuming they have low hanging branches, they almost always get the snot scraped out of the ground around them. It also gives a built in yardage marker, which can be critical in making shots more than most credit them for. So long as it's just a couple, I see it as 6 of one, half dozen of the other. In other words, it doesn't make much of a difference either way.
P.S. Only one of your food plots are a combo of shape and size that even the most mature buck would feel exposed in them, and that one is leaning far more to him feeling safe than exposed. I wouldn't do it for the "feeling of safety" factor, in your case. For me to leave them, it'd have to be for a different reason (too big to remove, wanting the acorn production from an oak, yardage marker, for increased scraping or just because I thought it'd look really "cool").