Have you assembled IKEA wall cabinets?

I bought all the cabinets for my kitchen 5 years ago but only installed the base cabinets then. I planned to put up the wall cabinets eventually and just unpacked them today to assemble. These are the Akurum boxes with the Nexus brown oak doors and side panels (that conceal the light wood boxes on exposed cabinet ends. Now the problem: the side panels on the bases were 30 3/8", the SAME height as the boxes. Why are the side panels on the wall cabinets 32 3/4" or 2 3/8'' TALLER than the boxes?

These are going to look horrible with the side panel extending 2 3/8" beyond the box. Why do they do this? I looked on their online catalog and I notice some side panels are 30 3/8" yet some are 32 3/4" but there is no explanation why. They discontinued this finish style 2 years ago so I can't exchanged them. Do I have to saw these off to shorten them? How do I do that without the foiled MDF shredding?