The bitcoin markets appear to be mirroring western markets in that the currency value has fallen. The dollar has almost perpetually decreasing value, and bitcoin is following it.
Surely when the dollar is taking a tumble, bitcoins should be worth more dollars than they were before the fall?
Right now most of the money by individuals is part of their disposable income. When economic conditions deteriorate people generally have less dsposable income so some of the people who have money tied up in bitcoins will be forced to sell them in order to pay rent, buy food, etc. This may or may not be happening right now but until it becomes adopted widely enough that people can pay for the basic necessities of living with Bitcoins it will always be subject to this effect.
And if not, how can bitcoin be tooted as a great way of protecting value (like gold, etc.) if it is tied to the dollar?
Value can't be stored in a currency whether that currency is metallic, fiat or electronic. For the most part value is produced as it is needed just before being consumed. Currencies are means of exchange but can emulate the ability to store value under certain limited conditions.