I never regretting removing ours.
I would regret putting one back in.

i really prefer a runner on stairs... we've always had one- never just bare stairs for long, so maybe it's what i'm used to- but i prefer walking/'running' on carpeted steps. when i've climbed up/down stairs without carpeted steps, i find the bare wood to be slippery, but then again, i rarely wear shoes in the house and i rarely go up and down steps slowly and carefully i guess!
(and, i like how runners look!)

I love the way runners look.

I hate carpet of any kind on stairs. It's too hard to vacuum and with a runner, you'll have to vacuum the carpeted part and dust the bare part...double work.

I own a carpet store and make custom rugs. Over the years we have "dressed" hundreds of sets of steps. Besides the Decor aspect of dressing your stairs with a runner, a runner will help with safety and reduce falls. The other aspect is that a runner will definitely add to the decor of your home and is a transition between the upstairs and downstairs. Also, a runner will "Enhance" the stair area.

Here is a link that might be useful: Stair Runners on Pinterest