Spamming Lucas Arts message boards will accomplish nothing but make some poor forum moderators day (or evening) a whole lot more annoying, and the guy likely has absolutely no control over what happens beyond than updating the website, more than likely.
Lucas Arts, to my knowledge, flat out does not own the rights to Sam & Max any more. Those reverted back to Steve Purcell, and obviously we have new Sam & Max games, by some of the very people that had worked on that canceled sequel I know we were all looking forward to. In fact, we have ten and soon to be eleven, new Sam & Max games. Not to mention a plethora of great new art books, poster prints, a fantastic soundtrack, and even a new release of Surf in'.
Do I think that Lucas Arts needs to take their heads out of that dark place near their naughty bits? Indeed. They have let some great properties go to waste because they could not open a web browser and point a search engine at the vast amount of cries from fans of everything from Full Throttle to Monkey Island.
If you really want to make your voice heard, do something like Hero1 suggested. Build a well thought out form letter, allow people to send that to the PR department of Lucas Arts where it will have a better chance of someone whom is in a position to deal with this and present it to the proper people.
Bashing Lucas Arts, a company with more money than they probably know quite what to do with, while maybe fun to some, at the end of the day, is just pointless. Yeah, I miss my Zak McKracken, Maniac Mansion/Day of the Tentacle, Beneath a Steel Sky days. And let us not mention the massive amounts of greatness that came out of Sierra back in those days.
If you take a look around though, Adventure gaming is not nearly as dead as people think. I do not need to mention Telltale, and obviously some titles tied to them like Samorost, but Phoenix Write, Fahrenheit (or Indigo Prophecy as it is known in the states) are just a few of the many great adventure games to come about in the past few years. And we will always have the old classics. I will not even begin with the indie stuff that is out there, and some of it, is absolutely fantastic.
But hey, to each their own, have fun with whatever you guys do (or have not done, I skimmed the thread and based my reply off that, take it for what you will).