Did you know that Erwin Nestle intended this to be the case? He wrote in the introduction to the 25th edition that his book was set up with the sigla and apparatus for those scholars "who want to concentrate on the text itself, without noticing the variations." He said that scholars "will easily get used to overlooking these signs."
Did you know that the Nestle-Aland edition is not a full critical edition? It doesn't contain all the textual variants. In fact, to my knowledge, we do not yet have an edition of the manuscripts with a full accounting of all the variants.
I understand that there is a project in Germany that is ongoing to solve some of this trouble. If any of you have further information about this project, or other publications, that are working to give a full account of the manuscripts, please let me know in the comments or by e-mail. Let's pass around this information this month, and get on top of what is going on in textual criticism these days!