I agree with gbulmer that providing the ability to do a tabular layout would be very desirable, although I would vote for implementing this in the print statement. This would enable LCD, Ethernet and any other classes that inherit print capability to also align columns of values using the same code. So my vote is to add some simple formatting capability to print that controlled the width and padding of a printed value would enable a sketch to align columns on any output device that supported print.
That's not to say that serial monitor would not benefit from enhancements, particularly the support of'\r' so that output can be kept to the same line.
But if Arduino core development resources are limited, then more sophisticated Serial terminal functionality can be obtained by using one of the many open source Serial utilities that can be downloaded for free.