As a statistician might tell you, rather than seeking to validate the absolute importance of an issue from a single sample, it can be a lot more enlightening to take a comparative approach. In this case I see that compared to other brands, printer forums with "clogging" threads combined with the Epson brand, are much, much more common than "clogging" threads combined with the Canon or HP brands. (No "brand-wars" please)
As for "expectations", I think it's reasonable that a printer will work for a long time before becoming unusable without major expense. This a reasonable user expectation. I think that if auto makers can offer 5 year, unlimited mileage warranties, large format printer makers should be doing something similar.