I kind of agree with what you are saying here in regards to strengthening up front.
I don't think Arsene will refuse to strengthen the attack out of principle, but it is more a case of I don't really see there being any top class forwards available in the January market to upgrade the team/improve the squad immeasurably. Ultimately I think Arsene will gamble and stick with Theo & Podolski supporting Giroud.
Will that take us over the line and cement our position as the number one team in PL? I don't know, but I do know that I would feel a lot more comfortable with a quality addition like say a Benzema or Diego Costa or someone like that. I might sound greedy but either the above would be great buys but if we don't decide to enter the market we should aim for the best in the Summer and aggresively pursuit their signatures, I.E. A Suarez or a Rooney.
The summer market was where we really should have strenghtened the attack...but we didn't and we are where we are.