Let's answer that by asking another question .... why do other companies have so many products?
One of the reasons is catering to market fads and another is design obsolescence. It's something that car companies figured out a long time ago, if you make incremental changes to a model, you create a desire to upgrade without having to innovate in any meaningful way, reusing the same platform for years if not decades.
Its very similar in the computer case industry, with many brands using the same frame (even sharing them) and just creating a new front panel every year.
Rather than pandering to the latest seasonal trend, we try to create designs that are timeless and that cater to specific demands rather than a multitude of overlapping products and features.
This also helps reduce waste which is an important global problem that needs solutions beyond simply reducing packaging usage.