to the original poster - you sound slightly frustrated. do you feel like your spontaneity is intimidating or have you been with guys who want things to be predictable? can you share an example from your experiences (and would you even want to)?
+1 I don't think you mean to, but it sounds like the OP is generalizing a bit. There are probably men out there that are more spontaneous than you.
I'm personally not a spontaneous person and have some spontaneous friends that make me appreciate the trait.