As long as they are fun I do not have a problem. I personally loved NSMB2 and 3D Land on my 3DS and was happy they made them. When I get around to getting a Wii U I will get NSMBU and 3D World (along with Galaxy 3 or what ever they call it).
Mario games have consistent quality to me and the plat former genre is not saturated in this era at all.