Update: while starting listener after the machine reboot helped on the first time, it didn't help on the second time.

See, I started the listener, go to dbca, and created the database using ASM. Of course it worked at the first time. Alas, during database creation process, dbca failed to extent a SYS table because the SYS tablespace is too small (my fault).

So, I restarted the server again, started the listener and the +ASM instance, and ran the dbca.

Guess what, it didn't work the second time; displaying the dreaded error message again:
DBCA could not startup the ASM instance configured on this node. To proceed with database creation using ASM you need the aSM instance to be up and running. Do you want to recreate the ASM instance on this node?
And this is really frustrating, because I did EXACTLY THE SAME STEPS with the first time (starting listener, starting ASM instance, etc). And the first time I did it, it was successful. I wonder why it failed on the second time. Same steps, different results --the very definition of insanity.

By the way, haven't I told you folks that I hate ASM so much?