When you first get on an airplane you are going to notice that the aisles are very narrow. Aircraft approved roller board suitcases (22 inches) are going to barely fit down the aisle. If your suitcase is just a little bigger than 22 inches it probably won’t fit at all. You’ll have to turn it sideways (not a problem if your suitcase has 4 wheels) to make it down the aisle to your seat.
Why are the aisles so narrow? The main reason is to make the seats as wide as they can be. The airlines have made the seat pitch (your leg space in front of you) as compact as possible in order to put more seats on each plane. But they still try to keep passengers comfortable by offering other amenities such as in seat entertainment (TVs), more comfortable seats, and making the seats wider. To make the seats wider the aisle has shrunk down to just wide enough for drink carts.
A good strategy for dealing with narrow airplane aisles is to make sure your suitcase is the right size (22 inches) and avoid buying wide suitcases. Having a 4 wheel suitcase allows you to take it down the aisle sideways. Also pulling your suitcase behind you gives you much better control than pushing it.