a patchwork of ethnic stereotypes
True, but aren't they all? Although I do note that its contemporary, LIVE AND LET DIE, is always the one that gets slated in this department, while the equally "offensive" MAN WITH THE GOLDEN GUN usually gets a pass.
cringe-worthy humor
Okay, but it's surely more sophisticated than the humour of the Brosnan era, by and large?
obvious product placements
I can think of only one, and I'm fairly sure I've watched TMWTGG more than most Bond fans (no, I'm not asking for a medal

) - "Nick Nack, more Tabasco!". Okay, I'm sure I could think of other bits, but it's hardly one of the worst-offending Bond flicks in the product placement stakes.
When the girls are in the back of the car, their dialogue is obviously a continuous loop. They say "hello" about five times. It's remarkably obvious, even if you don't speak a word of Chinese.
From memory, it's an unlikely mixture of Mandarin and Cantonese (see also LETHAL WEAPON 4 for this). But, hey, it's a Moore Bond movie!
Why does Hip drive away, leaving Bond to fend for himself against Hai Fat's goons? How in the hell does this make any sense? Hip risks his life to bail Bond out in the first place, then decides it's too risky and drives off.
*Fanwanking furiously* Hip is actually a double agent in the pay of Scaramanga or his Chinese paymasters. He spots a chance to engineer the death of James Bond, which will gain him great face with his employers, etc.
I'll skip the obvious stuff about J.W. Pepper and the Thai AMC dealership. Let's just say it would have made as much sense to put a McDonald's on Crab Key.
Why? Crab Key's uninhabited, Bangkok isn't. Why wouldn't the city have car dealerships?