For starters, hokkien is only a majority dialect in Penang... In KL its Cantonese or Hakka, for example. Much like (British) English, if there was going to be formal education in a Chinese dialect it was going to be Mandarin in line with what both the ROC and PRC did, since the whole point is to eventually enable everyone of Chinese ethnicity to communicate in a common tongue ( that isn't English...)
And in those days of the early 20th century when the foundations of formal education were laid if one was an educated person it would have been either in Mandarin or English (that said HK Cantonese is/was a huge pop culture influence but I don't think it ever was in an pan-sino educationist sense)
since the whole point is to eventually enable everyone of Chinese ethnicity to communicate in a common tongue ( that isn't English...)
Yeah, the strong desire to do that is something I don't understand. But thanks for getting to the crux of it - it's all about having a chinese exclusive lingua franca.
This really isn't that hard to understand, much the same way English was adopted as a lingua franca, Malaysia's Chinese population is itself heterogeneous and so at the national level the lingua franca of the Chinese nation, mandarin, is adopted over that of the disparate dialects that only had local superiority at city level.
A unified Chinese identity takes precedence over the local one, this is even more so when you are at the mercy of divide and conquer techniques. The only other alternative was Cantonese but then why would the Hokkien buy into that and vice versa? Educational resources are thin enough as it is.
And in those days of the early 20th century when the foundations of formal education were laid if one was an educated person it would have been either in Mandarin or English (that said HK Cantonese is/was a huge pop culture influence but I don't think it ever was in an pan-sino educationist sense)