Learn Turkish: Ulaşım kolay olduğu için bu koy çok cazip. - Because transportation is easy, this bay is very attractive.

In Turkish, you cannot put için directly after an adjective to mean 'because something is [adjective]'. You must turn the state of being into a noun phrase using olmak (to be) with the -dık suffix. Olduğu için translates to 'because of its being,' so ulaşım kolay olduğu için literally means 'because of transportation's being easy.'

Shouldn't ulaşım have a genitive suffix (ulaşımın) since it is the subject of a -dık clause?

Strictly speaking, subjects of these clauses do take the genitive case, and you will often hear ulaşımın kolay olduğu için. However, when referring to a general, uncountable concept like 'transportation' rather than a specific vehicle's transport, Turkish speakers frequently drop the genitive suffix. Both are acceptable and sound natural at this level.

Is koy the same word as the imperative of koymak (to put) or just a typo for köy (village)?

It is neither! Koy is a noun meaning 'bay' or 'cove.' It looks exactly like the command form of koymak, but context makes the meaning clear here. It is also very easy to confuse with köy (village). Just remember that a village by a bay would be a koydaki köy.

Could we use çekici instead of cazip to mean 'attractive'?