Easy - half the conference venues don't come with dongles, or if they do the AV guy is dealing with a crisis in one of the other 17 conference rooms and won't be able to get to your one within your 20 min slot (this happens A Lot. I do have my own HDMI-VGA though, but the VGAs seem to by dying out thankfully).
SD cards - I've never had an SLR or a high end mirrorless camera (but i haven't bought either for maybe 18 months) that's been able to transfer through itself at anything like the speed of a fast SD card in the slot. Makes a big difference when you want to dump 64GB of pics. As for dust, my favourite camera has been to Syria, the desert southwest of the USA several times, morocco, antarctica on a sailing ship (so being sprayed a lot), and not to mention my local beach. Aswell as just being the camera i throw into my shoulder bag when going out. Unless the photographers in your own office are war photographers or dirt-bike specialists, I've probably given my kit a harder life than they have. I've never had an issue with pushing dust into the SD slot of my camera or laptop. I did however dent the ISO knob on my camera when trying to tether it to my laptop when sailing across drake's passage, and a wave tipped the boat and I instinctively grabbed the macbook and let the camera hit the deck. I learnt my lesson. Fair point on micro SD though, but I have never used them for photography. I would probably be concerned too about fumbling, especially if wearing gloves.