Maybe then there should be some Victoria II scenarios then, rather than just tacking them on to the end of a game which isn't really about that era in the first place? Extending EUIV to 1870 would be like adding a racing mode to Crysis: sure, racing is fun in other games, but that's not what Crysis is about. It messes up the narrative and displeases two audience at the same time. Half the customers are disappointed that so much effort has gone into something that EUIV isn't really about (at the expense of the rest of the game) and the other half are disappointed that the end game features aren't nearly as good and accurate as they should be.
The arguments against extending the EU timeline are similar to the arguments against devoting large amounts of resources to RotW countries. Although EU runs for quite a long time, it isn't a sandbox like Civ intended to portray all situations, eras and countries equally. It has a specific subject, a specific narrative to tell.
It is not likely that there will be any other scenarios for Vic2 than 1836 and 1861, because it is extremely difficult and time consuming to make new scenarios in that game. This is not my opinion that is the opinion of Paradox developers on the Vic2 forum...