too much hassle really... lets calculate
3 seconds to take off the roof every single time... 2 seconds to place the roof some where unobtrusive...
3 seconds to put the roof back on at the end of the day..
Let's say you do this once a day for the life of the keyboard 20 years.
that's 16 hours of your life... FOR WHAT
Lets say you let the dust settle... let the keyboard die in IDK half that time, and buy a new keyboard...
8hr * $7 minimum wage $56.. No cleaning ever...
You start to see why the trade is not worth it...
The case doesn't really add up in a dusty environment where without cleaning a nice mechanical keyboard for maybe a day or two. Dust makes the keyboard look dirty and used apart from the fact that maybe accrued dust over time may start affecting the performance of the keyboard. Now in a rather undusty environment it may take several years (maybe even never) but in an extremely dusty environment, dust can start accruing up within the gaps within maybe a few years. Keep packing those dust down and eventually over several years those compacted dust may add some friction when pressing the keys down. Sure the effects are minimal but is it really worth neglecting?
Another case is that a good keyboard if well looked after will not only last the user a long time but also it gives the user intricate details on disassembly/assembly of the keyboard. Dirty keyboards for instance shows how one cares little for their keyboards. Now imagine if one never cleans the insides of their computer if using the same logic (except case gets extrapolated). Imagine the poor components gather dust to an extent that it may start clogging up fans for instance. Imagine if one also does the same thing with a car, never washes their car because there is no point to worry over such "trivial" issues. Can you imagine the sort of impression you would give others? On one hand you don't care about your belongings, you only care to use it as it is and all the dust issue for instance is all superficial but apart from that they may think that you are either lazy and/or generally messy. Now imagine what if some say a mechanical keyboard geek who loves their mechanical keyboard sees your keyboard being left in an unkempt state. What sort of impression do you think they will make about you?
Had the case been a regular rubber dome keyboard I wouldn't have cared much about cleaning it, they are cheap, dime a dozen and put simply "throwaway goods" once their useful life is more or less up. Sure one can treat a nice mechanical keyboard the same way if all they do is spend money solely on a mechanical keyboard. I wonder how long will that last for under extremely dusty environment one is living under. Probably one would have realised that it would have been an expensive sort of hobby to go through mechanical keyboards on roughly the similar sort of scale as rubber dome keyboards. Not to mention that the money could have also been spent elsewhere and also one would have learnt something when cleaning their own keyboard apart from showing love to the said product.
Besides a keyboard roof is not solely used to guard against dust. It can be used to sort of cover against liquids being spilled onto the keyboard provided that the user was diligent enough to keep putting on the roof whenever the keyboard when not in use. The cover provided may not be that great but it is still better than nothing. There is no way to know when will accidentally spill liquid on their nice mechanical keyboard but in other cases it may sort of pay for its worth apart from being a fashion accessory that one may see it as a "labour intensive" job to take the cover off and put it back on.
When it comes to harder sort of keyboard roof like acrylic roof, the roof protects the keyboard from accidental key presses when the keyboard is to be stored away. It protects (when maybe for instance stuck together via masking tape) the keys from being pressed (and decreases the life of the switch on the key) when transporting the keyboard in say a car when it is in motion.
Last but not least, keyboard roof can also be because of "honouring" traditions. I have seen with the some old school typewriters, they have keyboard roof which one puts over the keys. Not only does it look nice (as it still more or less does with modern keyboards which are normally plugged into a computer) but it maybe seen as some old school habit. Keyboard roofs adds a bit of a touch to a keyboard apart from all the possible reasons above. Though I guess it wholly depends on users' preferences.
There is one notable mechanical gaming keyboard which has a keyboard roof that also doubles as a palm rest when in use. That is probably one of the ways to make a good use of the roof provided that one has the adequate desk space for both the keyboard as well as the palm rest. Had maybe other manufacturers considered about doing something fancy with having keyboard roofs to make sure that it would be a sort of "waste of space and time" there maybe more other users that may see the benefit of having a keyboard roof.
There is nothing wrong with your comparisons but the way you phrase it sounds like the small things are of a big deal whilst overlooking at the benefits of having a keyboard roof. More like you loathe keyboard roof. To me a keyboard roof offers some distinct advantages apart from simply the fact that it is only seen as some sort of fashionable accessory.
