There is a "completionist" mentality amongst some of us...where we want most of the red rings even if our shooting style does not support the lusted-after purchases. Canon of course will gladly take our money; I think Canon has some of the best marketing strategist working for them.
I bitterly complain about weight here in the forum...being mostly a people photographer, someone like me even lusting after the 600L is just plain silly... And I don't. My shooting style doesn't require it, even if I could afford it, it is highly unlikely I would be able to carry it, or appreciate its full worth. It is clearly a superb product, but it is best left in the hands of those who will use it to it fullest extent.
I would be a completionist if I wanted the supertele just to have this range "covered"...how often have we heard similar refrains in so many guises? "Oh I need the ultra wide range covered...don't have a sharp lens there"...
The fact some of us shoot landscapes now and then does not make us a landscape specialist who needs to lust after the 14-24 L that doesn't even exist yet! The fact we took a semi acceptable picture of the tufted titmouse that visited our bird feeder doesn't make us a bird photographer who needs to lust after the 400 f/2.8 IS II.
Completion-ism also drives us to collect or strive toward artificial groupings like Canon's "holy trinity"...if you choose 35L as a standard then there is perhaps a case to be made for getting the 85L and 135L.... There is enough spacing between them. But say if you truly loved your 50mm as your standard? Then the 35L is not that far, so most chose either it or the 50L. But here is the kicker...in this case, some recommend that you add the 24L instead to complete an alternate "trinity" along with the 85 or perhaps the 135L.
Onerous as the original holy trinity concept is, at least it losely encompassed the classic portrait lenses... yes, even the wider 35mm. But how applicable is 24L on a routine basis to people photography? You could argue that you take street shots with 24L, and surely 14L can take pictures of people...but that is not the most common use for these wide-angle lenses. This alternate grouping straddles disparate styles of photography unlike the original somewhat "cohesive", albeit still artificial grouping.
And why stop at a trinity? Why not a "penta-perfect?" or "super-six?". Or instead of the holy trinity...I'll make something up here...how about we stop at the "divine duality?" Say, 50L and 135L?
So "completionism" makes us invent artificial grouping; like a hapless magpie, it goads us to collect things we do not need, use frequently, or employ to their fullest ability.
Stop the madness and look at your shooting style first; get the best lens you can afford in that range. Strive or dream about updating to the highest quality lens in that range as finances allow over time. Dump the idea you need an L in every single focal range that ever existed.