American basswood is a specific species so it is the only type they would be referring to but there are other species of basswood. I live where a lot of it grows, it dries really quickly and burns fairly good too, we used it as firewood when I was a child
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Economically it's a good wood to use, it grows fast and large, it's easy to carve and work with, it's consistent, and it's cheap. The only problem is like you said it sounds mediocre in most cases, it's not the worst but it's down there on the list.
Ibanez makes a good guitar, I just think they do need to make more models like the Xiphos where the combination of woods is of higher quality in regards to tone.