bikurim and mitzvos hateluyos ba'aretz

Adding to the previous post, I think perhaps R' Chaim Brisker's chiddush regarding challah also applies to bikurim as well. Tosfos (B.B. 81a) asks why a seperate pasuk is needed to teach us that bikurim only applies to the fruits of Eretz Yisrael - doesn't that din logically follow from the fact that bikurim is a mitzvah hateluya ba'aretz? (Note as well that the Rambam hil bikurim ch. 5 cites a pasuk to teach that challah applies only in Eretz Yisrael but does not cite a pasuk by terumos and ma'asros). Tosfos answers that terumah is considered teluya ba'aretz because the obligation of hafrasha rests on the fruit, without which the fruit is considered tevel. Bikurim is not a chiyuv inherent in the fruit but is a chovah on the person; the fruit is not prohibited before hafrasha. The definition of teluya ba'aretz is where the cheftza of being a growth of the land creates a chiyuv, not simply a chovas hagavra contingent on a person being located in Eretz Yisrael.