Please make the guides lockable so that they aren't continually moved whenever trying to resize an object whose handles are near the guides.
Agree that feature would be great. Having them on the master page does not help either as unlike other elements guides on the master-slide are not getting locked – which does not make any sense to me whatsoever.
Also a guides-grid creation tool would be amazing
Jamie Garroch commented
Guides currently support three different layers. Slides, individual Slide Layouts and the Slide Master. So you can add guides to the layout or slide master and these cannot be accidentally dragged when in the Normal view. We are about to launch an add-in within May (2018) that will do this for you. Here's a sneak preview: https://twitter.com/YOUpresentUK/status/991109119603068929
In PPT 2013 and beyond, you can put guides on the masters and layouts, which effectively gives you what you're asking for.