I'm not sure how to expand much more, but I'll try.
Every art - as it is taught (so this can vary somewhat by instructor) - has a "feel", and often a type of motion that is somewhat distinctive. Judo is more push-pull circular with tight movement, and Aikido is more accepting circular with broad movement. I know some folks in Aikido who would say those are opposing and clashing approaches, but I find they fit together nicely. Okay, so that's two circular arts.
Shotokan is linear and angular. Surely that would clash with the movement and feel of Aikido, but I don't think it does. The habits of moving that way can make it harder to learn circular movement at first (assuming the Shotokan is first), but once you get past that part (or if they are trained together), they turn out to complement well. Early in the process, the angles of Shotokan fit nicely into places that would have been a "mistake" in the Aikido (stepping off-line, too far away). As that progresses, the Shotokan gains some circles and some of the circles in the Aikido shorten or change planes, becoming more upright. Some even flatten and become closer to direct response.
Everthing I've played with or studied has fit together for me. My primary art is Nihon Goshin Aikido, which primarily moves with circles. Our strikes are not generally circular (derived ostensibly from Shotokan), but our movement to them still follows the movement patterns from Daito-ryu, because that's our base footwork and bodywork. And the strikes still work nicely. The bits of striking I picked up and recall from Shotokan, Tang Soo Do, FMA, boxing, etc. all seem to fit nicely into Gerry-fu. The grappling I've picked up from Jujutsu (probably derived from Wally Jay's), BJJ, Judo, FMA, MMA (mostly BJJ base), etc. all seem to fit in, as well. I occasionally find a movement pattern that feels "off", but I've almost always been able to find an adjustment that makes the technique work for me. A few times I've run into techniques that didn't work for me, but I chalk that up to either esoteric techniques (I think most TMA have some techniques that are there for a purpose other than direct application) or just not having enough time to understand the real principles.
It might be that having a hybrid base art makes this easier to learn, but I think it goes back even before my experience with NGA. At one point in my early teens I was studying Judo and Shotokan at the same time, under the same instructor. That might be the formative time for my acceptance of different movement.