No, you don't need them.
But my experience on Nost and Ely (pservers) tells me this (which why the pservers HAD to change BL spawns to dynamic):
The inner circle (upper echelon) of the guild that farmed them for AQ40 and Naxx will REMOVE YOU from the raid if you DONT buy their flask. They will use bank alts (that you cannot link to them) and set the price at 240g+ per flask, and then offer you the flask on the main for 80g+ as a "kind gesture."
If you don't like it, you can leave the guild and they'll happily take someone in shit gear to replace you just for them to buy their flask.
This insane level of coercion and "black lotus mafias" (all of which you can GOOGLE) is what forced Pservers to change Black Lotus spawns in order to retain their clients.
Live Well and Prosper @
HordeFanboy !
(btw, they even give you free flasks for the first two weeks! how nice of them!)
- - - Updated - - -
After serious thought I have come up with three solutions to the black lotus problem:
1: Make Black Lotus decay after 7 days, this will prevent people from stockpiling and purposely choking the market by withholding them.
2: Dynamic respawn on Black Lotus based on server population.
3: Create 50 spawn points per zone.
All of the above are required.