I've owned my 5-string for about 18 years, so I usually expect the low string to be a B if I hit it. I've only recently purchased my new 6-string. I love using chords because they sound very clear. It's also nice to have access to a full 2 octave range within a span of 4 frets.
Exactly. However, I think, that as some others here have hinted at, a 5 string bass, and a 4 string bass, and a 6 (or more) string bass are kind of three different instruments.
A 4 string is definitely "old school" and plays all those old basslines developed by the masters perfectly. I learned on a 4 and played one for many years.
However the whole time I kept feeling this "limitation" especially in horn keys (Eb) etc. My first 5er was like sky opening up, clouds blowing away and rainbow lighting up! Lower notes. No "key" problems. nice patterns across the neck. I was home.
A 6er is a different thing. If you start to go to higher notes even on a 4 string you may notice the way the force of the bass tends to "drop out". So an extended higher range isn't really about the same thing as an extended lower range. So you have to ask why would you need higher notes? And then you'd have to ask why did Jaco have to use harmonics to get higher notes? Point is that higher notes are more melodic. They make chords that aren't muddy. They let you solo into the stratosphere. So do you "need" that? As a few have pointed out here, it pretty much depends on your music. A while back all I was playing was my 6s. Now, all I need is my 5ers. later it may be 6s again. How often do I need to chord up against the guitars or double a melodic line high up on the bass? Depends, right? When I need it, I need it!
And lastly, though I'm still woodshedding my 7 string, so far my assessment is that it's sort of the same thing as a 6 only even MORE melodic. If you listen to guys who really can play the high "n" basses, the upper range is basically a melodic thing. So right now I sort of see 6,7, 8 etc. string basses as all sort of the same kind of thing. Which is rather different from a 5.