Actually they made 3 full movies about Vader being a whiny punk. I think Kylo Ren is a far scarier and more interesting character. It is somewhat why I liked the mask but I understand how you can't pull off these plot points with the guy in a mask. I also think an actor of the ability of Adam Driver would never take the role if he was going to be in the mask for three films.
Agree on Driver. Also on Leia - really tough to imagine why they didn't let her go right there - it would have wrapped up the loose end and also allowed Kylo to have even more rage and confusion at his dark side/First Order lot. Maybe even more importantly, it would have removed what I think is the the worst scene in all the saga (including anything Jar Jar). Although I will say I have seen many comments from viewers saying they found the Carrie Poppins scene to be moving, to the point of tears. I thought it was cringe worthy and embarrassing, but different opinions.
Lastly, with such an iconic image (both the special effects of it and the gesture of self sacrifice), how did they NOT make it Leia who hyperspace missiled Snoke's ship to save the Resistance? Talk about a fitting end for one of the best characters in the series. The Holdo character was extraneous and unneeded like several other plot devices in the film. I know she is in the books and has a long history with Leia but from the films (which is what 90% of viewers know), she seemed like a random and the relationship had zero development. Also she wasn't notable, likable, or relatable in any way. Huge missed opportunity.