A shareholder is not paid "interest forever".  The dividend payout is created by corporate profits which are not guaranteed.  That being said HEI's payout ratio of 83.34% is very high when compared to other similarly situated utilities.  It leaves little money to maintain and upgrade infrastructure.

If indeed  "It’s actually more attractive when the share price falls because the return rises." shareholders must be ecstatic today as the stock price has declined from US$34.40 on June 28 to US$30.53 on todays close.  That drop of US$3.87 equate to a loss of about 12% of the invested principal.  

The actual current dividend is US$1.24.  Assuming that HEI maintains its dividend at the current rate, which is unlikely given the mindset of the PUC and Representative Lee, it will take over three years for the dividend to repay shareholders the US$3.87 that they lost when the merger proposal was rejected.  

It's true that HEI doesn't invest its earning into infrastructure, that is the problem