Shouldn't the main criticsm here be aimed at the whole Rugby League community who can't even fill Wembley for international games involving the national side, nor for one of the two showpiece events of the year, whereas the RU community can fill it for a normal league game?

Union has a much bigger fan and player base, particularly in the "casual" fan category. Clubs may not get huge crowds week in for normal games but there are lots who have little affiliation but would turn out to a showpiece event just for the beer and the day out.
I was at London Irish Sunday for the game against Leicester (the St Patricks day manufactured marketing event). Frankly I barely noticed the game, it was a day out for our entire minis section (and for 15 other clubs). It's a comfortable stadium and unlike when they play football there they actually treat you like adults and leave the bars open all through the game and after.

I don't know why we don't fill wembley anymore for CC or internationals (well maybe here the small shred of optimism we all had during the 80's and early 90's has finally been crushed out of us).

theres lots of local rugby games going ahead in the london area but its usually taking place at the same time as the bronco's games so local rugby fans cant get to see the professional game
i really hope that they draw a big crowd to the game at leyton orient as it might get barry hearn interested and he does know how to market events, a ground share offer from him might offer more benefit than the quins one as it puts the broncos nearer the heart of london

The majority of London fans (and I know that's still not many) choose to sit in the Wset Stand which is where the cameras are for Sky. There was a spell when they made us sit in the East so it looked better on TV but that was never the most popular move (the seats there are further from the pitch and when it gets to Summer the sun is in your eyes).

I think it's a legitimate argument to be seriously concerned about the lack of progression in the attendances. Catalans just 9,000+ for a game against Widnes - progress we have never seen from the Broncos - Im no expert but after all the time and money invested shouldn't there have been some positive signs in terms of attendances?

Like trying to flog Buddhism in Southern America.

Considering the vast majority of clubs struggle to be profitable or improve attendances even in the heartlands, I think criticism should be directed elsewhere than at London. As tvoc said, they should be supported not slagged off as some people do.
Personally I think the RFL should be doing all they can to find a very rich owner for London, Sky/News Corp being the most obvious.