The point, if Yahtzee did mean this as a point, is that games should evolve/improve with each iteration/generation.
For various other products (iphone, processors, etc.) each generation is supposed to be an improvement over the 'old gen' and, for the most part, this tends to be true. People get better at making things, new tech, etc. etc. There are still the general hiccups like bad factory, mess up in manufacturing, etc. but 'ideally' there should be a 'bare-minimum' expected and delivered, plus maybe a little extra with each iteration.
His criticism of Super Mario Galaxy 2 is not that it is a 'bad game' per se, but that it doesn't change anything or bring anything new to the table. It is Super Mario Galaxy 1, re-released with some polish/make-up.
To continue on this point (of evolution of games), he arbitrarily decided to look at the history of "time traveling games". He could have easily picked "RTS", action, or anything else.
RTS might have been easier if it is just the 'game evolution' point, since there is Starcraft 2, and all the other RTS clones, etc. and what not and there is a 'clear' evolution (or lack thereof) in all the RTS games since Dune by Westwood.
However, the evolution of 'game genre' probably isn't what he wanted. He wanted the evolution of a "GAME MECHANIC". Time-travel not as a story or backstory, but as an actual game mechanic and how it has improved/changed over time.
I am not 100% sure why he picked 'Future wars'. It could have completely replaced "time travel device" to alternate dimension device/portal and it would work out just as well. He may have picked it as the 'beginning' and 'worst' iteration of time travel as just 'backstory' instead of a game-mechanic.
There are then two 'main' types of time-travel mechanics in terms of games.
1. 'long' global Time-Travel. Mainly in changing the setting. I.e. you are at the 'same' place spatially but different temporally and there is a relatively large gap of time in between (years).
Chrono Trigger, Day of the Tentacle, etc. would fall under this. You change the time but it is the same 'world'.
2. 'short' local Time-Travel. This is for all the action-oriented/instant time travel/forward/rewind of seconds or longer and can rewind 'localized' space. i.e. just you, or just some object.
Prince of Persia, and other action games with a 'rewind' mechanic would fall under this. I haven't played Braid yet (i own a copy) but it seems like it would fall under this category as well.
Either way, games should either
a. Improve upon the 'normal' time-travel mechanics
b. make up a different 'good' time-travel mechanic (a point 3).
If you are going to outright copy a previous game's time-travel mechanic without any improvement (or potentially making it worse), then there should be other improvements/polish that would make me want to play say, Singularity, over just going to go play a different game that delivers everything I want.
This could be the point Yahtzee is trying to make. Of course, assuming that everyone is logical and has a 'point' would self-destruct if we analyze Chris E.
Corv