Imagine if the usual mortgage were 25 years of interest-only ... & etc.

Paying simple versus compound interest payments makes a difference, other than that .... yeah.

The usual bond payment structure is insane ...

Can't argue with that, either.  Before the Loot and Scoot School of Management came 'round it was possible for companies to amass a sinking fund which, in theory and occasional practice, was used to retire the debt.  Now that pile of loot is mere fodder for the predators and makes the company even that more of a take-over target.

Add interest payments are an above the line tax deduction and dividends (cost of equity payments) are an after tax disbursement, and the debt/equity ratios get shoved to the debt side.  

Adverse conditions leading to gradually increasing debt principal ("deficit") are "ponzi finance", at which point the entity is vulnerable to a run

I firmly maintain ANY system containing a unregulated - of whatever nature - positive feedback loop WILL jump the shark/reach a Tipping Point.  The singular, exact nature of such is dependent on the focus or 'core' of the phenomena or phenomenological system undergoing transition.  For banks it's a run.  For Logisitic systems it's our old friend the Feigenbaum Logistic Map.