Merchants, the masters of identification, don't get infravision.

Tarmies, the masters of healing and assistance, get neither heal self nor
regeneration.

Priests, the masters of harming, don't get tiger claw.

And even the most devoted of poison mage can't get spider wrath.

The fact is that just because a spell exists that you'd like to have, doesn't
mean your guild gets it. True, there are some "utility" spells like light or
see invisible that find their way to scattered guilds, but not all of them.
This is one of the things that makes having 2 guilds a good thing. It's not
just about the guild's theme, it's also about balance. Maybe we don't want
maxxed tarmies getting floating disc, just because it's teleportation and they
joined navs. It's not that it's too powerful (unlike, say, giving disint to
reavers, which would be wrong in so, so many ways) they just don't need it and
it doesn't fit the theme so well. Perhaps you've noted that many spellcasting
guilds get one, maybe two, teleport spells, and it's usually a different two
than other guilds. It's the same idea.

As for only getting 100% cast teleportation at level 5...well, if you look at
other guilds, you will be hard pressed to find any that have a skill/spell
that advances more than 20% per guild level. The exceptions are rare and
usually located at the top of a guild. Navigators just don't have the levels
to spread it out. Besides, why do you need cast teleportation to 100% when you
only have the spells to 40%? If you're that concerned, take a look at the
average cast teleportation of the guilds that allow joining navs. Most of the
"pure" casters, such as conjurers, already have 50 to 100 percent and don't
mind the slow poregression.

Shinarae Lluminus