So when it comes to actually exploring the world, there's a huge difference between the guy who got to Quelag through the depths and blight town, and the guy who got there through the darkroot basin past havel, or better yet through new londo. A major difference in what you'll have already fought against, what spells and equipment you'll have access to, etc.
But this example is kinda all there is - Undead Burg/Parish and the available routes connecting it to Blighttown is pretty much the whole of DS1´s interconnectedness, at least from the perspective of how it affects routing (visual connections don´t). There´s also the Lost Izalith shortcut and that´s it.
I don´t think areas like Sen´s + Anor Londo (including Ariamis and Duke´s), Oolacile or Great Hollow + Ash Lake are much, if at all, different from Catacombs - Tomb since all of these also feature single access points. I mean, I´m not sure if the fact you can get to Anor Londo without setting foot in Depths is something that sets it apart from, say, Shaded Woods, which you can reach without setting foot in, say, Forest of the Giants.
Personally if I had to describe why I consider DS2´s world layout (how areas are aligned with each other) less impressive than in the predecessor, it would boil down to three points:
a) lack of equivalent to DS1´s central loop (Burg/Parish, Depths, Darkroot, New Londo, Blighttown) - I don´t think the loop itself is necessarily a must have requirement for world layout to be on par with DS1, it´s just that I don´t think DS2 features anything comparably cool
b) linear post-Shrine of Winter area sequencing
c) skyboxes usually improperly, or not at all, reflecting adjacent areas
When it comes to the amount of routing possibilities though, taking the presence of DLC trilogy into account, I consider the game ripe with more than DS1, at least when it comes to content available pre-Shrine.
The paths to Great Souls may come with mostly linear area sequencing, but they all can be unlocked really early and bonfire warping is available from the start which opens the pre-Shrine parts to all kinds of progression antics and the first two DLCs also provide an element which was quite missing in comparison with DS1 - a possibility to delve into areas not required to open the game´s big progression gate (1M SM bypass aside), á la Catacombs or Great Hollow, except without dead ends. All three DLCs can also potentially notably mix up the otherwise mostly linear post-Shrine progression, or can even be fully left to post-endgame, opening possibilities to take advantage of late game vanilla items without going to NG+.
On top of that, the game has more areas to begin with so for most of the time there´s just more stuff to pick from.
At the very least, personally I can say that decisions of which area to tackle next come up way more often when I´m playing DS2.
I don't understand those who sequence break in Dark Souls. I can't speak for others, but for me the boss fights are the main attraction. Why on earth would I wish to skip any of them?
It's not necessarily about skipping them, but about taking them on in a different order.
Which I´d say is something DS2 is just as, if not more, open about.