these icons aren't representing the company, they are tools used for software that the company produces. You can educate your bosses/decision-makers with examples from your competition's software (or other modern software).
You certainly need additional information before you waste everyone's time with a redesign. Find out what the goal is regarding a re-do of the icons - are they looking to enter a new market segment with the new release? Or are they just trying to make something look like it's intended for the 21st century, instead of the 20th.
Personally, I don't like to limit the color palette for icons - the more distinctive each one is, the easier the users will be able to quickly tell them apart. However, you can offer a limited color palette that can be pre-approved by management before the icons are designed.
I second the suggestion regarding The Noun Project - while monocolor icons do have their place, the icons in that collection are a great reference and inspiration for creating your own.