There is a difference between a stepped rate load and a variable rate loan. The problem with the housing industry is with stepped rate loans - that is why they went up even though prime has not. It was written into the contract to keep initial payments low, but with the knowledge thaat payments would increase later. It was the PAYMENTS that ballooned, not the interest rates on the mortgage.
Variable rate loans are tied to the prime rate. You look at almost every credit card contract and in the really teeny tiny print you'll find that the rates are prime plus X for the base rate and prime plus Y for the "default" rate. Prime increases, so do both the base rate and the default rate.
Also, people with lower rates do not necessarily have lower personal debt. In fact quite the opposite is likely. People with high risk rates are also usually tied to lower maximums. Even though their total debt is lower, they are closer to their maximums, causing their credit rating to drop, and their interest rates to increase. People with high limits can have a significantly larger total debt, yet still have a lower percentage of available credit, thus having a better credit rating which keeps their rates lower.
For instance, a person with a spotty credit history three credit cards, but they are limited to 2500 each. They have a total of $6000 distributed between the three cards. That means all three cards are close to their limit. By being close to their maximum, their already spotty credit rating is kept lower, and their interest rate will be higher.
Another person has a clean credit history. They have 4 credit cards with a maximum of $10000 each. They have $18,000 approximately equally divided between the cards. Even though they owe 3 times what the first person owes, they have a better credit rating that is not negatively affected by the debt because it is below 50% of their available credit. The better credit rating keeps their interest rates lower.
Now both people have, through bad planning, gotten themselves in debt enough they are very seriously struggling. But both are also managing to barely) hang on the couple years in their fight to climb out of the hole. Now they are both facing a marked increase in their transportation costs, and food costs, and power bills, etc. Now they are not balancing on the edge, they are starting to slide down the other side.
Even if an increase were to strengthen the dollar immediately, you KNOW the price at the pumps will not decrease in response to cheaper market oil anywhere close to how fast pump prices react to oil price increases. Nor will other inflationary pressures be relieved except after a three to six month lag. Most prices, including that of gasoline, are unlikely to go back to their pre-crisis levels.
But you can bet the credit card companies will be sending out notices of rate increase due to the prime rate going up within a day of a prime rate increase. The rate increase will add to the costs of inflation, and the delay before the rate increase will do anything about the inflation, could well send people like in the examples over the edge, disrupting their ability to maintain payments on their debt so they end up with even worse interest rates, thus making it even harder to climb back out of debt.
Inflation alone is bad enough. But add interest rate increases could end up spiraling people on the edge down into irrecoverable debt.
Oh, and shall we mention the effect the prime rate will have on the daily cost of the national debt?