Consider the effect of an increase in expected profits, say from a spurt in productivity. To the extent that higher expected profits reflect higher expected future output and income--and not just a redistribution of income from labor to capital--both economic intuition and formal models suggest that desired household spending should increase, all else equal.
Consumers foresee their future higher income and want to spend some of it now. That response is a straightforward wealth effect on consumption. Now consider instead the effect of a decrease in interest rates, setting aside for a moment the implications of the interest-rate decline for investment and future output.