This makes sense, since there are a larger number of more diverse levels in SMG than in M64. I disagree with your tedious assertion, as replaying the same few levels over and over against in M64 got a lot more tedious than the more varied level design on SMG.
It's a combination of things that makes SMG feel more tedious to me. For one, I really enjoyed hunting the stars in the M64. Yes, there are many hidden stars in SMG, especially SMG2, but there was just something appealing about actually needing to read the hint for most of the stars in M64. The hints aren't really hints at all in most cases with the SMG games. Just keep moving forward and you'll get to the next star. I think this is largely what kept the M64 worlds feeling fresh for me.... the hunt. Just about the time I was getting tired of a level it was time to move on anyway.
While the world appears more open, like I said above, you still have to tackle each star a certain way. There is no real added non-linearity. SMG just breaks levels up into each star section, which does funnel you towards the targeted star, but also provides a more focused gameplay experience where you don't have to go through the same areas 6 or 7 times.
I disagree with this. Yes, stars are in specific locations with often specific ways to acquire them. But within each world it was definitely largely non-linear. In most cases you could get any star in any order and more or less had to hunt them down. In the SMG games, you just keep going forward and the game will force you to the next star. You may have to hunt for some of the hidden stars, but unless you're actually going for all the stars you can stick with the main listed stars and have enough to keep progressing in the game... at least as far as I've played thus far.
More tedious than collecting 100 coins in each M64 level? I think not. Not only are they much easier to collect and can be collected on the side while hunting stars, but you don't even have to walk up to them! Just moving the cursor over star bits collects them, making collecting much, much less tedious.
Well, admittedly, that was tedious at times too. But I still prefer that over the star bits. For one, collecting coins has been a Mario staple from the beginning. Two, it's me playing as Mario collecting the coins. In SMG it's me, the player as the hand of God waggling the stupid star cursor all over the screen, collecting most of them. That just serves to separate me from the game, and as mentioned before, that really bugs me. Plus, I don't like having to collect some obscene amount at once to feed those hungry Lumas. Also, you didn't need to collect any of the coins in M64, that was just the way to get one of the stars in each level. At times in SMG you must have a large number of star bits to advance down a path to new levels. It's the difference between getting a single star in a level and just gaining access to worlds with multiple stars. I'd simply prefer that they weren't in the game or that they were at least not required to advance to certain levels.
Your points are valid, but I still find it hard to believe that someone who hasn't played M64 first would like it significantly more than SMG. I think that nostalgia has a strong power over perception of video games.
I'm sure nostalgia plays a role, but I still prefer the level structure of SM64. The SMG games have better graphics and a lot of new creative platforming elements, but they still feel like I'm playing a collection of random arena challenges on floating junk rather than a cohesive Mario adventure set in Mario worlds. I think you could take many of the platforming elements found in SMG and use them in a more open M64-like level structure. That's all I'm really saying.
Also, despite my tone at times, I really do enjoy SMG2. I bailed on SMG1 half way through due to boredom and tedium, but that doesn't seem to be happening with SMG2. BTW, I LOVE the side scrolling levels. That's my preferred method for linear Mario levels. I think those plus the much improved level navigation is what's making the difference for me with SMG2. I could still do without the star bits, but so far I've simply lived with it because the platforming is so solid.