I used to travel on the Blue Line for work. Seeing people with suitcases is No Big Deal, even during rush hour. Everyone knows that line goes to O'Hare, and everyone expects to see luggage.
The polite travelers either put their suitcase on their lap, if possible, or tuck it as far out of the way as possible. Sometimes, though, people have a large suitcase, and there's simply nowhere to put it. In that case, people just stand next to it like it's another person taking up space. If someone has their suitcase on a seat, you simply ask if they can please move it so you can sit down.
I see no point to discouraging someone to use the Blue Line, especially since it's only $5 to ride from O'Hare to the Loop. I'd much rather tuck my suitcase next to me just like everyone else than do the hop-skip-jump to the Metra, especially considering Metra's schedule. If you aren't traveling during "rush hour", you wait anywhere from 2-4 hours for the next train. The Blue Line departs every 4-10 minutes and is easily accessed from Terminal 2.
If you don't want to haul luggage up the stairs at Clinton, you do what I mentioned in my first post: get off at Jackson, which is an accessible station, and hop on the #151 bus on Adams St. Easy peasy.