The story is still being told. Give it chance before you slate it.

It might turn out that the Thrawn storyline explains it all nicely. Equally though, it might not.

The entire Hosnian System including the New Republic capital was destroyed by Starkiller Base. Most likely, any defensive fleet they had was in that system, and was destroyed along with it.

The New Republic was heavily demilitarized. What fleet they did have was destroyed by Starkiller Base. Plus, like someone else said- the story is still being told.

The Star Wars story isn't finished yet, though.

Pretty sure they specifically said when the Hosnian System got wiped, the New Republic defense fleet went up in smoke with it

^ Yes indeed he did. The ships were shown above Hosnian Prime.

Dunno why they were all there though. Maybe an end of term party.