At least Tierkreis still felt enough like a Suikoden game because it was still about a band of ragtag commoners that get drawn into a larger conflict. The thing I disliked the most about it was the villain, they just weren't interesting.
Hyakunen was crappy because it was a "monsters blowing up the world" story and had almost nothing to do with Suikoden, gameplay or universe wise. At least Tierkreis had 108 stars and still had several gameplay elements. Lard constantly complains about how it was just thrown together or whatever even though he never played the game, but Tierkreis was undeniably still a Suikoden game, even if you want to say you don't like it.
Both games still fit into the Suikoden universe in the sense that they introduced the concept of the Infinity in like, the third game, but it's a pretty flimsy excuse anyway.