Taz and Marvin -- what's the deal?

Oceansoul, posting at the Golden Age Cartoons forum, wonders why the Tazmanian Devil and Marvin the Martian receive so much marketing hype despite their relatively sparse filmography:

Actually when you see any Looney Tunes merchandise or ad, you probably recognise either of the two very overrated character faces there. What's the legacy of the two characters to become so big merchandise faces of the golden series? OK, Marvin has one memorable episode (Duck dodgers), which I always considered a bit of overrated, but there are a lot others have even more: Michigan Frog, Gossamer, Henery Hawk, Rocky, Sniffles, Sylvester Jr, Witch Hazel... all of them are secondary stars but never got the same spotlight that Marvin got. As for Taz, he is even worse. Neither of his five shorts were great, Ducking the devil was average to good, but that's all. And he was hyped after the end of LT series, even got an own series, Taz-Mania.

Matt the Y provides a prompt response:

Taz was overrated even from the start. Even studio boss Eddie Selzer found him annoying to the point where he ordered McKimson not to make anymore cartoons featuring the character after "Devil May Hare". Jack Warner, however, thought that ol' Taz was absolutely hilarious and asked Selzer to reconsider his anti-Taz edict and he did. Thus, we got "Bedevilled Rabbit" and the remaining Taz shorts. Why J.L. found the character so delightfully funny is a complete mystery to me; sure, he's kind of funny but not that funny; what difference would it have made if he starred in more shorts or not?!

Anyway, to answer your question as to why Taz is just so popular in merchandising and otherwise, Jerry Beck virtually summed it up in his audio commentary for "Devil May Hare" on the first GC DVD; people can actually relate to Taz because he's the ultimate slob. He's always hungry, he's completely unbridled and untamed, and, as Mr. Beck himself put it, if you can actually bring yourself to imagine Taz's personal bedroom at his home, you can almost bet that it would be an absolute mess. People think that's cool; hence the bountiful merchandise of the character.

As for Marvin the Martian; I honestly never noticed that the character was that heavily merchandised. I certainly noticed the extreme over-merchandising of Taz; that's undeniable. Marvin much less so. But to answer your question, I can see how general audiences could find Marvin "cool"; he's an outer-space oriented science-fiction cartoon character with seemingly hostile motives (i.e. in two cartoons, he's intent on destroying the Earth; in one cartoon, he's intent on bringing back a helpless Earth rabbit to his home planet). That probably adds to his popularity; hence his bountiful merchandise.