So, when you form your religious opinions based on English translation you are reading "I baptize you..." which doesn't even describe what that means, let alone the manner of such act.
And Greek reads the same passage and sees "I immerse you repeatedly ... " and the two of you do not read one and the same thing. And that carries a completely different meaning. This is also an excellent example of how one's theology cannot be formed properly by simply reading any version of the Bible because all translations are corrupt. Thus, to a Protestant who makes up his or her own rules based on reading some Bible, there is nothing wrong with just immersing once. In fact, more than once becomes a 'tradition of men' quite erroneously based on erroneous reading. Once the error is set, errors proliferate.
Now, I will agree that thrice is probably a tradition that the Church adopted as the meaning of baptiso based on the trinitarian concepts, God's three days of burial before resurrection, etc. quite in line with Gospels' witness and not as something arbitrary or, worse, as a result of misunderstanding.
Absolutely return and focus on the original texts is important. If you listen to many English sermons though (the ‘better’ ones in my opinion), you will find that there is care taken to examine the texts in original languages as well. Similarly, it is never the text alone which enlightens us, but always the text read with the guidance of the Holy Spirit.
There have been misconceptions and poor teachings even when people have relied upon the Greek. I’ll have to examine your point on baptiso a bit later, but translators of the Bible in any language use the most extant primary sources as their guide.
Could you elaborate on which passages use baptiso, and which use bapto, as this might help clarify the point.