That does not suggest that the 150 flap switch type and position are unsafe. It was in service for long enough!!
You suggest looking at the indicator on the pillar (next to the screen where you are looking out) is less safe than looking down into the cockpit at the indicator on the lower centre of the panel.
It is also common knowledge the gate on the 152 switch gets warn with age and causes problems.
One advantage of the switch rather than stepped 152 switch you are able on go-around to take the flaps up in smaller steps, rather than 10% at a time. Or more if the gate is not as positive as it should be on a 152.
The 150 is like every other aircraft - they have a slightly different flap (and other systems) operation and requires the pilot to be familiar with the operation of the aircraft they are flying.