Have you ever found yourself wandering aimlessly in your improvisations? Sort of pounding the keys without any direction? That's because you lost track of meter. Well, maybe not only that...
Meter can be a single decisive factor between meaningful and meaningless performance. Between your audience asking for more and being puzzled of why you keep playing if your improvisation has ended a long time ago.
If you like 3/4 or 4/4 meter, keep counting the quarter notes diligently. Keep emphasizing the downbeats. If your message requires it, you can use changing meters but your choice has to be a conscious one. The round of 2/4, 3/8, 3/4, and 5/8 will make your playing quite unpredictable but coherent.
For those of us who improvise in a modern medium, irregular meters provide freshness of ideas. If you could play a section of 2 minutes long in 7/8 or 11/8 meter, then suddenly your improvisations will grasp the listeners by the throat and won't let go.
Whatever you do, don't take meter for granted. It's vital for the impact of your composition.
Meter creates flow. Flow creates interest.