Personally, I think you're approaching it from the wrong angle. Nobody devalues a sprint win for thinking it "easy".
For the most part, sprint stages are felt to have less value for many fans simply because of their abundance, but mainly because they seldom have special or defining features, nor do they typically have any long-term impact because in stage races (other than ones like the TDU which have relatively low value anyway) sprint stages seldom have any relevance to the outcome, and in most one-day races of any value they don't end in field sprints, except sometimes the Worlds (in which case many of the flatter editions like Zolder and København are derided for lack of spectacle) and Milan-San Remo (where the sprinters earn their chance to compete for the win by getting through the distance and over the climbs, so nobody devalues them doing so). Very few sprint wins are memorable and therefore they may as well not have happened a couple of weeks after the fact.
The reason sprinters' salaries reflect their value is that, while some stages are inherently more memorable than others in any given stage race (quick: who won stage 3 of the 2009 Vuelta?), prize money is equivalent. Any GT unless incredibly poorly designed (hello, 2012 Vuelta) will need some transitional stages to get from area to area, and so there will always by necessity be some sprinters' stages. In fact, across the year, sprinters have by FAR the most opportunities to compete for the victory, and therefore, unless a team has one of the few bonanza GT candidates or a dominant Classics rider, having a good sprinter is an important way of ensuring a constant stream of prize money. The "value" of sprint wins from a purely monetary perspective is equal to those in any other stage of a given race. The "value" in terms of esteem amongst the fans is, quite obviously, not, unless something unexpected has happened. Abdoujaparov's most famous win is his hilltop solo in Tulle. Hushovd won the Worlds, but apart from that it's the 2011 Tour when he soloed in after chasing Roy and Moncoutié down off the Aubisque. People hold Milan-San Remo and even the Aubenas stage of the Tour higher than the København Worlds in Cav's palmarès.