Normally I would consider it a minor point; however, the thought occurred in my last game, when my summoner cohort was tied up, that depending on how the ritual is required, he could summon the eidolon to help him escape.
There's also a point in the text that says the ritual summons the eidolon to your "side." That begs the question of distance or not.
*edit*
Distance would matter for situations such as stuck in a jail, a sneak attack, or numerous other situations.
*edit2*
In reply to Rocky, I thought about the distance from the spell as well, then it occurred to me that there are things about the spell that are different relative to the normal summoning - retains weakness to certain protection and doesn't stick around. It also requires a silver coin for the spell which is - assumingly - not required for the ritual (maybe?)