I think if somebody says your bass playing is too busy, you should take it seriously, and assume that they are responding to something real. But what exactly is that something?
A bass line can sound too busy. But as many on this thread have observed, that is not necessarily because there are too many notes being played. The accurate rhythmic placement of each note's attack and end can make a huge difference, and sometimes concentrating on this will cause a "busy" sounding line to suddenly snap into place and sound great. Timbre is also very important. If Chris Squire played a JAmes Jamerson line with his usual Yes tone, it would probably sound ridiculously busy.
So I feel there are three general areas You might change:
1) actually change the number or rhythms of the notes you are playing.
2) change the placement and articulation of each note. Rocco plays lots of notes but the attack is very accurate, and each note is muted just right so its sustain doesn't get in the way of other instruments, or disrupt the groove.
3) change your timbre. You could scoop the mids, roll off the highs, boost/cut the lows, change where you pluck the strings, switch from pick to fingers, palm mute, etc.
Some combination of the above suggestions will fix the busy sound, but it's a very individual thing. The same line played by two players might sound busy for one and perfect for the other. Like anything else, it's something you learn to do as you become a better player.
One more thing.
I am one of those tone-obsessed players. If my sound isn't right, I don't play as well. Part of that is that I hear timbre as part of the groove. When my sound is good, whole and half notes sound wonderful, and I have no problem playing 1-5 all night long. If my sound is thin and clacky (due to my technique, the room, the amp, whatever), that's when I am tempted to play more notes to fill in what seems to be missing. So sometimes, getting your sound "right" can fix what other people think they are hearing. Easier said than done of course, but maybe thinking in those terms might help.