> Interest rates would go down to match the deflation rate for that reason
The market clearing interest rate would probably go down, sure, as would the quantity of money lent.
Demand for credit would drop (that is, the amount that people would be willing to borrow at any given interest rate would drop), because the real cost at any given interest rate would be higher.
Supply (the quantity of money lenders are willing to loan at any given interest rate) would not increase, though. It might naively seem they would at first because the value of the payments on a loan with a given principal and interest rates would seem to be more, but in relation to the value of just holding the money in cash there would be no difference, so nothing to drive an increased propensity to lend.
So, while interest rates would probably go down, it wouldn't be a source of benefit to lenders, it would be a consequence of the decreased attractiveness of borrowing.
> Also many people argue the same thing about printing money to cause inflation being a continuous upward transfer of wealth.
Inflation is a downward transfer of current wealth (more precisely, its a transfer of wealth from net creditors to net debtors.)
Insofar as inflation has a negative direct effect on the less wealthy, its because it decreases the real value of income streams of fixed (or pegged to some index that grows slower than inflation) income streams, and the less wealthy are more likely to be dependent on such streams.
OTOH, inflationary currency is a big part of what makes such streams (defined benefit pensions, etc.) possible in the first place; so a deflationary currency wouldn't actually make that situation any better.