Interesting observations. Using some examples from my neck of the woods, I'd say it could be mixed up with agriculture and migration patterns.
Vietnamese is very strongly future-typed. No tenses but an auxiliary verb 'se' = 'will' which appears in front of the verb. It is used even when the word 'tomorrow' or 'this evening' appears in the sentence. Vietnamese are famous for their over-indulgence in alcohol and coffee, although culturally they're savers (in the form of gold or ornaments). Oh, and they're atrocious drivers. (And there's a Catholic influence - sin now, confess later.)
Thai is even more strongly future-typed, in that their word for 'will' ('ja') takes even more precedence in the sentence - eg "ja mai pai Pantip" - "I will not go to Pantip". Thais are known for their moderation in most areas and they're characterized as undisciplined when it comes to wealth/savings. But they do drive well. Talk about Thai attitudes and most foreign observers will sum up with "mai pen rai" ("no worries").
Both the Thais and Vietnamese are rice-growing societies who recently migrated (the Thais much more recently) from China, where they're very loose with future markers.
Contrast with the Malays. Spoken Malay has no future typing - they rely on words like 'tomorrow'. Their society is characterized by its indifference to planning and saving, feasting today, forget tomorrow. Not very organized agriculturally. They're also an island race - perhaps best not to think too much about the future when you're getting into that boat and you can see nothing on the horizon (but a full belly will help).