You say that this is the intent of the verse. But perhaps it is to liken this coming (i.e., your coming to Egypt) to that coming (i.e., your coming to Eretz Yisrael) — Just as the first was optional (and not mandatory), so, the second! It is, therefore, written "to inherit it." You are coming to inherit it.
The difference between the first and the second — the coming to Egypt is optional; the coming to Eretz Yisrael is mandatory. In coming to Egypt, they did not count shemitoth and yovloth; in coming to Eretz Yisrael, they did. The land of Egypt, whether or not they did the will of the L-rd — here is the land of Egypt for you! Not so the land of Canaan (Eretz Yisrael).
If you do the will of the L-rd, here is the land of Canaan for you. If not, you will be exiled from it. As it is written (Ibid. 7:12) "And it shall be, if you hearken … then the L-rd will keep for you His oath," and (Vayikra 18:28) "So that the land not vomit you out by your making it unclean."