You would not be wrong there if Rice is the best defensive midfielder in the world but he isn't. It is debatable whether he is even the best option out there. Plus, it's not as if the other options are useless or that their club want to insert a buy back clause.
Take a short term hit? If West Ham don't want to sell now, what makes you think they will sell in January? If we don't get him now, we'll very likely have to wait till next summer and given our midfield problems right now, can we afford to wait until then? Are we gonna spend the next 7-8 months complaining about the stupid mistakes, the midfield setup etc over and over again and watch it cost us chances of winning games and maybe even challenge for trophies?
How is this the same as panic buying in January? We already knew for the longest time possible that the midfield is a problem for us and we have had the whole summer to address the issue but we haven't. If we don't get anyone in now, chances are we won't buy anyone till next summer and we'll see and complain about the same old problems repeatedly over the season.