Possible ill effects form removal of fuel thermostat

[europower]

1987 300d
Fuel thermostat hoses were cut and ft bypassed, i assume someone had a leak and didn't want to mess with replacing the o rin in the thermostat.
Is there any ill effect from doing this on the 603 long term??
Im in Northern California with pretty mild temps year round

[jt20]

I have read some things that suggest its main purpose is for fuel efficiency in wide temp ranges.

I have mine removed and I am farther north than you.