My initial thought is that summoning made exp rates sky-rise which resulted in less pride when attaining 99 in other skills: it also made attaining items easier so the value of items dropped as well. This is the first and most important example that comes to mind.
But, you may have a further point, Mojo. Perhaps it is not only the 'we need more skills attitude' that ruined the game for me since the interface/display/playing experience of rs3 also leaves a bad taste in my mouth. This leads me to recognize that perhaps I really am hesitant to vote yes to any big changes because they can snowball into the creation of a game which i don't like from one which I love. I know this is not inevitable but I watched it happen and I am worried it will again. Call me old fashioned (or illogical for falling to the slippery slope fallacy) because I am irrationally scared of change, but I watched a game I love die (to me) only to be resurrected thru osrs.
I believe Jagex is adding skills primarily for new players; to gain a larger player base. Profit rules and more players equals more money. But, osrs was brought back because players respond to the simplistic format of the older game. Why? I have no clue and can only guess. Therefore, too many changes can lead to less rather than more players(even if these same players who end up leaving initially thought they wanted the changes only to find they didnt after its too late). <--This is one reason I think the polls should have less questions because it is difficult for the average player to do the background reading for every question being polled.
My personal belief is that the formula for the perfect game has already been found in osrs. Further tampering is only going to get away from the heart of what old school scapers respond to. As I said above, add new content thru the skills already in-game; add more armor, weapons, spells; take them out if they are broken, but don't reshape the game by adding more skills for the sake of novel material to promote in order to get more players to play osrs for a month or 2 before they leave for the next game.
The rs2 I knew did not have any of these skills except for summoning; I quit around the time dungeoneering was being released.