Many people only knew about The Witcher with 3, same for MGS and 5, and even for Fallout 4. One of the basic principles of game design and marketing these days is "we have to make a game for people who have never played (our) games before". Remember Mass Effect 3's marketing campaign? "If you haven't played any ME game yet, this is the perfect place to start!". You could argue that part of the success of the rpg kickstarters from last year was based on the fact that they marketed their products to jaded audiences who wanted something they could feel more comfortable with. As it has been said, some of the people who are complaining about cut out and/or simplified features from FO4 are the ones who knew about the franchise with FO3, but the former isn't for them anynore, this is a game for a new generation.
In contrast, compare this with all the franchises who died in the mid-late 90s because they changed too much stuff.
Some people think the simplification of dialogue - which is hand in hand with the voiced protagonist - is bad because it was designed in a clunky way. Some people even expected 100% cinematic mode and cutscenes during conversations, even. Some of them are being lenient because they think Bethesda will improve this in the future, but in the end the answer is the same: mods will fix it.
People who already complained with FO3 won't be happy with 4 or any future FO game, because, sadly, the game does not "belong" to them anymore.