In my own undergraduate degree, I noticed a distinct positive correlation between professors who didn't make their slides available deliberately ("so that you don't just skip the lectures and read the slides at home") and professors whose teaching I would rate lower-than-average. One of these professors taught so badly that I skipped his lectures anyway and just read standard textbooks on the subject; I ended up with a top grade.
I would speculate that teaching with the attidude that "most students are here to learn with goodwill and I'm here to help them" produces better teaching than the attitude that students are principally lazy and I'm here to force them to learn. I'm a researcher with occasional teaching duties myself now and I'm very strongly in favour of teaching materials always being available to download.
Here are two arguments in favour of making slides available. First, what if a student misses one of your lectures due to illness, injury or because their train broke down on the way? (This is not a lame excuse - we had a cluster of genuine cases one summer when the trains couldn't cope with a heatwave.) Would you rather they were able to revise the lecture themselves with the slides, or not?
Secondly, my experience during revision for exams is that even with notes of my own, slide printouts are incredibly helpful. Partly this is because a printout of a slide is a visual aid to jog your memory and remember how the thing on the slide worked; partly it's because you have two sets of "notes" (your own and the slides) which is better than one, partly it's because making notes on a slide with arrows pointing to the relevant parts is so much more effective when diagrams or pictures are involved than having to copy down the relevant points as text alone. If you have a complex diagram on a slide that you're explaining, do you want your students to be spending your lecture trying to copy it down, or do you want them to be paying attention to your explanation, safe in the knowledge that they can print out the diagram (or have already done so, and can annotate it without having to draw it first)? A rhetorical question, I know, but I think this point is important. Finally, everyone sometimes makes mistakes in their notes and being able to cross-check against the slides is very reassuring.
I'd summarise by saying that for a motivated and good student, having the slides available allows them to use their revision time more effectively, and will lead to better results.
There's one caveat here though. As discused in  and just about every "how to give an effective presentation" book and talk, the worst kind of slide is simply a list of bullet points with text to copy down; a really effective slide to support your teaching will have very little text and so be of limited use on its own for someone who has not attended your lecture. Some of my best professors had slides like this and provided us with extra "lecture notes" handouts; it's a standard I aim for in my own teaching when time allows. I leave you with the thought that if your slides are this good, and support your own teaching rather than holding a lecture in parallel to yours, you won't need to worry too much about students opting to stay at home and just read your slides in the first place.
 Good slide design for teaching?