I doubt if its marketing strategy. Computers sort thru billions of optical formulas running around the clock finding those that are candidates for products. Those are then checked by a person, and mostly found impractical or lacking in some way. There are, of course lots of formulas dor a $50,000 lens, but finding one to produce for under $3,000 is difficult.
The marketing part comes in setting priorities. There are five or less lens development teams, producing a new product about every other year. We don't know what priority they might assign to a new wide lens as opposed to say a new 100-400mmL. Then, there are the video lenses and the EF-s lenses that all use the slim resources.
I'd like to see both.