What is a refined sequel? Well it's more or less when a sequel is different enough to be a step up from a rehash, but not changed enough to revolutionize the series.

This is actually a good thing. Not all sequels have to be revolutionary. It's largely for when the series has gone stale. Otherwise, constantly reinventing the wheel would just be an unnecessary creative strain on the developers. 

(Okay, Final Fantasy mixes it up a lot, but the series has a long history of that anyway.)

Now being a middle ground, there is actually a lot of range. Twilight Princess is one of my favorite games, but apparently Ocarina of Time was so polished, it left little room for the former to grow outside of simply being a bigger, better sequel to the latter (in terms of refining the series, without revolutionizing it).

At the other end, we have what I consider to be the holy grail of refined sequels, Super Metroid. If Metroid II hadn't already introduced most of the new power ups, I would consider it a revolutionary sequel (for the same reason I consider Super Mario Bros 3 to be a revolutionary sequel, due to all the additions). Yet I still love it because it took everything good about the first two games, and made them awesome.

The point here is that is why some sequels seem to work, even though they don't reinvent or innovate drastically (like a certain, recent sequel to a megahit series). Sometimes the series just needs a nip and tuck. 

I like long term franchises myself, once i get to know a character i want to play as that character as much as possible, so i will agree with you, change what is necessary but keep the series the same in the areas that made it great.

I agree- for example, the Super Smash Brothers franchise, though it really did not innovate from entry to entry, has refined itself and gotten better with each installment. Another example is Half-Life 2. It's an even better game than Half-Life, but without much revolutionary, except the gravity gun.

I agree.

Which makes them great to play. I still think they should probably take a hit in reveiw scores though if the first game of the series was revolutionary... not "It's this game, but now it's better so it gets an extra arbitrary 3 points."

I guess because to me, you aren't really judging the game. You are instead judging the creator of the game. Much how many modern movies are more technically advanced yet older movies get better ratings. Even when often times the modern movie is a remake of the classic with a few things changed for the better.

I tried to think of a sequel that was actually truly different and revolutionary compared to its predecessors and came up with nothing.

How do you define that? And why would games like Super Mario 64, Ocarina of Time, GTA III (in terms of compared to previous GTA games), and Metal Gear Solid not count?