https://www.lawnmowerforum.com/showthread.php/52096-Kawaaski-FR651V-FX-air-box-conversion
I guess that would be a pretty cool feature to have installed somewhere on your mowers engine and yes there are some who definitely need some sort of "visual" reminder that their mowers engine Filter(s) needs to be either, cleaned or replaced, etc.
I can see that feature being very beneficial for those individuals who use their mowers far more than just regular usage, either heavy residential usage or commercial use. Then yes that particular feature would definitely be a big plus factor.
Though, speaking for myself, I always tend to follow what the Service Manual says to perform on my mowers engine concerning this (without any type of extra reminder).
That's just the way I am. I replace Spark Plugs, Oil Filter, Fuel Filter, Engines Pre-Filter and main Filter regardless of what the hours indicate. Again, this happens once every year for my ZT mower.
But I also take it a step further and as previously stated, basically just give my mower a basic tune up every early Spring regardless of the amount of hours showing on the gauge.
My mower really doesn't get heavy usage, it has low hours, currently gauge shows 43.2 hours for little over 1 acre of land to cut and I've had my Hustler ZT mower purchased brand new since 2016.
Below is what the Service Manual for my particular manufacturers engine says about it.
I used to perform the same thing on my previous riding mower (old YardMachine with a Briggs & Stratton engine) and also had that purchased brand new back in 1997 and it lasted me till I purchased my current Hustler ZT mower in 2016 (so you do the math) and it never failed me back then, always kept going.