Is being Lawful Good the "optimal" way of playing PS:T?

This.

I hold this game to be to RPGs what I Have No Mouth And I Must Scream is to point-and-clicks. Play it multiple times, with a different mentality and wildly varying moral compass each time, and see all the various endings you can get.

Only if you plan on using the 2 items that you can find in the game that give you a +1 increase to constitution each. There is a late game weapon you can acquire that requires that you be Lawful Good in order to use it, but there is another weapon that you can find that has no such restrictions and is pretty good in its own right.

Aside from that, the only affect of alignment is a change in a certain boss that you have to fight. Honestly, I hate the concept of alignment as a known force, aside from the fact that it tends to result in some DMs turning their games into overly reductionist "Good Guys versus Bad Guys" campaigns and the fact that it is an overly simplified attempt to define morality (something that even the greatest philosophers have wrestled for an insane amount of time without arriving at a definite consensus), is that it is so easily broken. When I played PST, I played a character that registered as Lawful Good; however, I did so with the mindset that being nice to people seemed more likely to payoff in the long run, both by earning me swag and improving my reputation among the locals. The acts that the game treated were the work of a paragon of virtue were in reality those of a manipulative sociopath who put the Practical Incarnation to shame.

It really really depends on the GM you play with. And in any case the two-dimensional alignment system allows for much more flexibility and discussion than the recent one-dimensional ones...

Preach it brother!

In any such game playing "evil" is a wholly altruistic act where you must forsake wealth, fame, and power for the sake of petty cruelty and adherence to the code of evil. Which is a paradox on several levels.

DnD's implementation is especially onerous because its so mechanically broken and harms the game in so many ways