I have modules that are up to 8 years old... I have over 100 modules, from over 40 manufacturers & have had 3 failures in that time... one of which was a button... which was fixed for free by the manufacturer, out of 'warranty'... and another of which may have been damage in transit (used module)... this I had to get repaired... it was 60€ for the repair... as the module was an uncommon and out of production one this was my best option - it ended up costing me slightly over the original retail proce, which wasnt' that much to be honest - is it better ot spend 60€ (or whatever) to repair a module than to effectively throw it in landfill - of course it is... in reality some modules will not be able to be repaired, due to obsolescence of parts - particularly things like processors for digital modules - but this is unforeseeable in most part by hte manufacturer - although covid did cause other issues - basic unavailability of non-obsolete parts...
the 1 year guarantee is ok in most cases - electronics usually fail very early or very late... plus local trading standards "fit for use" periods would supercede this in a lot of cases (3 years for EU & 6 for UK) - although getting that enforced can be problematic - so modules usually either fail almost straight away - often component faults - or after quite a long time - longer than any reasonable guarantee or "fit for use" has run out...
I think you are massively overestimating the amount of failures of modules - like a lot of things - if you spend a lot of time on the internet you will find complaints about something... there may seem to be a lot of complaints - but in reality there are only a very small & of users, most of the time... a lot of the time there will be clusters of failures - due to the manufacturere buying parts in batches - and maybe one batch has a tendancy to fail much earlier than other batches - for some reason only known to the original manufacturer of the part - see leds, encoders etc... the small % of users with failures tend to be much more vocal than the larger % of users who are happy & just get on with using their modules
i don't buy modules for their internal memory... nor have I had any digital modules fail on me - except in the above mentioned button failure (which was an analog component of a digital modules) if you arre worried about this stay away from modules that don't have it or use sd cards for storage, but again see previous paragraph!
as far as quality of build/customer service/repairs to modules - I generally see that anything above the absolute cheapest modules - it's quite good - most manufacturers will repair modules - you may need to pay for shipping and possibly parts...
some manufacturers have poorer reputations in other areas - generally this also seems to be reflected in this area as well - so if you want good customer services, repairs instead of landfill etc then steer clear of manufacturers with dubious ethics etc
unlike in fast moving consumer goods, there is no built in obsolescnce - ie the item being deliberately designed to fail or become unrepairable after a certain time... modules are generally designed to work for as long as possible... but it is also impossible to guarantee that every module will work forever...
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities