These are good examples of what I'd call "the inflation of the public's expression of enthusiasm" that has been in place ever since the "Encore!" call and standing ovations started to be used as devices for the public to express their approval of the artist.
Standing ovations would be used in special circumstances, when the artist's performance was so spectacular it deserved an expression of gratitude and approval much higher than applause. Often only a subset of the audience would bestow standing ovations, since an opinion of excellence in the area of public performance is no doubt a personal one.
Today standing ovations are given very liberally. Worse still, you just need a "critical mass" of people to stand up and suddenly the entire room stands up. I stand up because the idiot in front of me just stood up and if I want to catch the last glimpse of the performers, I don't have much choice but to stand up thus contributing to this wave of inflated opinion.
Encore is even more interesting. Again, when the public took a particular liking to a performance, its members would collectively call "Encore!", asking for more. The artist would oblige. Today, not only does the artist perform an encore almost every single time; the public has in fact stopped asking for it, as if there was some kind of secret hand shake that happened between the collective body of all performers in the world and all the audiences in the world.
I don't have a big problem with it (a little bit of inflation is generally a good thing) unless the resource that is subject to inflation is bounded. In case of money, something can always cost a little more (I have the cardinality of natural numbers to thank for this, I guess--maybe Peano, maybe Cantor, I don't know). But I don't really have much of a choice when it comes to performances. What am I going to do if the performance has been truly spectacular? Am I going to stand on the chair? (I considered throwing roses but that seems archaic, and the logistics!--I would have to have bought roses ahead of time just in case the performance was good; such heightened expectations make it more difficult to really overwhelm me with a performance... lots of problems)
In the case of encore this inflation has reduced to an awkward (to an objective observer that happened to have been on Mars for the past thirty years, I guess) routine where the artist finishes his or her performance early (because they must leave the best piece for the end!), waves everyone goodbye (nowadays this also happens pretty lazily since everyone knows it's not the real goodbye), and then comes back after a minute or so (what do the artists do in that time? Enjoy their much-needed respite?). We live in a funny world indeed.