The founders (and many who followed them, including SCOTUS, see Kawakita) saw two potential pitfalls. One is that the president might have affection for his home country (be that by birth or upbringing), the other being that his home country has, in fact, a bona fide claim on the person.
Dual citizenship carries a potential for trouble and mischief.
Your point of view is that naturalized citizens should be allowed to assume the presidency. That is a popular point of view. It has been advanced in Congress several times.
Both valid points
Cruz was four years old when his family moved to America...I don't think four year old have developed an affection for their country of birth...Cruz has been here for 40 years, a Texan, Texas Solicitor General, and Senator.
Cruz dropped his dual citizenship so Canada would have no claim on him...
The potential pitfalls should be taken in context on who is running and why...
As an example:
I see far more dangerous pitfalls in a Hillary / Sanders Presidential victory than any pitfall that might be made against Cruz or Rubio...
My suspicion is the whole Cruz birther issue on FR is more of trying to knock out a potential Trump challenger than any REAL concern about where his loyalties lie...
Maybe I'm reading this wrong, but it seems almost all of the posters pushing this issue are ardent Trump supporters..