For one, perhaps "replayability" isn't the most important aspect when considering a game's structure and design. (That criticism always seems to pop up, not just for 4; that if a game isn't designed and paced for replaying, then it's poor design)
And two, just calling sections filler and padding doesn't make it so. Just because they slow down the pacing doesn't make them bloat, filler, and padding, if they're in service of the narrative and overarching pacing. You not liking those aspects doesn't make them extraneous
The "you not liking x doesn't make it bad" statement probably applies to GAF more broadly.
Well said, I was gonna do another paragraph post in defense of UC4's slower pace, but you summed it up well. Suffice to say, the transition from a bombastic Indiana Jones narrative of previous titles to the more personal, slower paced story told in 4 (my favorite hands down), certainly lost some UC followers who were expecting more of the same.
Gonna preface this by saying I have played UC4 three times:
The thing with UC4's areas with a slower pace is the character moments in between all of the arenas and set pieces were the best in the series. It has my favorite story and my favorite villains. The motivation of the characters, the twists, the Nate
tying into your journey with Sam and Sully, it all was top-notch. And then the actual gameplay? Some of the most seamless I've played in a game with responsive controls, a variety of ways to tackle each encounter, and some bombastic set pieces involving collapsing buildings, Crash Bandicoot-like chases, speedboats, and motorcycles. They take the cover shooter and turn it around, making it so you can't just stay in one spot with the destructible barriers but also giving you plenty of ways to get around areas and plenty of stealth spots in the large arenas.
I replayed UC4 in the past month in order to get me ready for Lost Legacy, and it very well may be my favorite Uncharted. This is coming from someone who loved 2 and 3 and liked 1. 2 is easier to replay immediately since there isn't as much downtime in 4, and no young Drake section as in 3. 2 is fantastic. I think 3 also is and doesn't get the credit I feel it deserves. It's a testament to how highly I think of 4 that I could consider saying it's the best.
I dunno if Lost Legacy could beat that (only on Chapter 4), but regardless, it does have the advantage of having 4's gameplay.