Time is important in both languages with and without tenses!
There is an joke that goes like this:
A European was wondering why a Chinese was late for an appointment. The Chinese replied casually, “You Europeans have watches, we have time…”
Well -> the message today is: many Europeans find it hard to learn Chinese, or Thai, or basically languages where tenses are not important. Similarly, Asians find it hard to learn European languages because they don’t understand why you have to change a tense when you can just say the time.
Hence, to an Asian-language speaker, it is perfectly fine to say “Yesterday is a good day.” Since you’ve already mentioned yesterday, why do you need to change ‘is’ to ‘was’? (In many Asian languages you just mention the time and do not modify a verb to reflect the time.)
To the European, he probably thinks -> “Oh, I could just say “It was a good day.” I said ‘was’, and in the last sentence I said yesterday already, so I don’t need to say it again and you know what I’m referring to.”
Perhaps this is why the Swiss are so good at making watches, and culturally to the Chinese, giving someone a ‘clock’ is interpreted as sending someone to his death… LOL. (It is true, never give a Chinese a clock…)
To sum up -> Time is important in both types of languages, but to different degrees of detail. Let’s learn to respect each other’s concept of time, and we can learn each other’s language more quickly… 😀