I wouldn't say they were a bad rifle, just that the M1 Garand was probally a better rifle. They have advantages, and disadvantages just like anything else. Yes they do malfunction with a bayonet attached (like every short-recoil rifle ever), however other than that they tend to be a pretty reliable system. A bigger factor in the short service life of the rifle was that it wasn't the M1 Garand. What I mean by that is that the M1 was already adapted and unless the rifle was significantly better (which the M1941 wasn't, it was comparable or slightly better or worse) it won't be replacing it (for example you wouldn't replace the M1 with a Johnson, however you would replace it with a M14 because there was some significant advantages with the M14 over the M1). If Johnson had his rifle made back in 1936 maybe the US might have adopted it over the M1 Garand, who knows.
Some Marines held on to them for a long time, here is a link to one that was held by a Medal of Honor recipient who used it all the way though WWII (even to Iwo Jima).
http://jamesdjulia.com/item/lot-305...recipient-captain-robert-h-dunlap-usmc-48279/