Bitcoin is currently inflating, no?
Bitcoin's monetary supply is increasing. The price trend on most scales is quite deflationary.
As for the alt coins creating inflation being same to fiat money printing: the difference is that the new alt coins are separate moneys. An alt chain doesn't print new bitcoins, but new feathercoins or ppcoins. So it's not the same at all. If the Fed started printing another money, like Monopoly money, would that lower the price of dollars?
It is, as the OP has surmised and I agree with, one of bitcoin's silliest shortcomings. Pandora is out of the box, and there will not be one cryptocurrency to rule them all in a deflationary system, because people will just use or create others when bitcoin is annoying. Alternatively, if you drop the pyramid distribution scheme, there is no longer an incentive to leave the currency for one that is less one-sided. An example if this is proposed
here.
When taken at different scales and time intervals, bitcoin will always have big periods of price inflation and big periods of price deflation because a fixed money supply is easily manipulated. Because of the properties of other cryptocurrencies follow the same scheme, bitcoin is ultimately relegated to being one of many. New, deflationary currencies are likely to be "the cure" for manipulation. Instead, if the money supply were unbound in the first place, everyone could stick around and live in utopia.