USB PC Current Limit

... do I need to or should I provide unrush current regulation on my device? The device is only ever plugged into a laptop/desktop. What are the consequences of not providing any inrush current regulation on the device?

"Properly" you should provide device side current limiting.

Worst case you can dip the power rail and cause an outage on other connected equipment or cause startup problems with the device you are connecting.

In practice I'd expect that most systems will survive plugging in capacitors substantially greater than 10 uF. However, if this did cause misoperation or even damage in practice you would have no grounds for complaint.

10 uF would have trouble pulling the skin off most rice puddings and even say 100 uF is not a vast amount of capacitance*.

But, if you did want to provide startup protection you should be able to achieve this with 1 x MOSFET, 2 x R, 1 x C and an optional diode.

The MOSFET is in series with the large capacitor - call it C1.
When power is off the MOSFET is off.
Place a resistor R2 across FET d-s to provide some startup current if desired.
Place a timing cap C1 from gate to source and a turn on resistor R1 from gate to supply.
At turn on the MOSFET is off. FET gate rises (or falls depending on whether low side N Channel or high side P Channel) and FET starts to conduct and then is fully conducting. By making R2 suitably low and turn on time delay from R1, C1 long enough the main cap can be charged mainly via R2. This is not essential but without R2 the FET needs to transition from off to on slowly enough not to cause inrush problems (still).

The current limit detection by a host mode device that emits current to a USB device may or may not be accurate. Here are the types of host devices that you are likely to find:

1. Some host devices such as a PC may have no limiting on the port itself. In such case a big overload of several Amps on the port may instead cause the internal 5V supply to shut down.
2. Other devices may use a conventional type of fuse that is selected to blow out at some load current over 500mA. That fuse may be rated at say 0.75 or 1.0 ampere and blow at a level above that depending upon the fuse characteristics.
3. It is common to find usage of poly-fuse type devices to limit the current. Similar to conventional fuses on the ratings side they will trip at a level quite a bit higher than the 500mA level. The advantage of this type is that they will reset when the overload is removed and the poly-fuse cools down. A downside of a poly-fuse design is that the trip current level generally increases when the device has tripped one or more times.
4. Finally there are host mode USB ports that are equipped with 5V USB switch parts. These are designed to support actually turning the port power on and off. Such devices contain actual load current sensors that can be more accurate than the fuse types described above. But to keep part cost low the sensors are not more accurate than say a 20% to 40% overload.

No USB host mode device designer wants to make a device that nuisance trips and causes grief for their users. For this reason it will be rare to find a port that supports USB power source cut off at 501mA. Instead the cutoff, if any, will be much higher from say 600mA and possibly up to the current limit of the internal 5V supply.

An interesting point is to open up the typical powered USB four port hub. It is not uncommon to find the internal circuit board designed to use the 5V port power switch parts. However likely as not the parts may not even be installed and instead be replaced by a direct connection to the 5V supply. The manufacturer may then use the same circuit board in several models of their USB hubs that are offered at two different price points. As you can imagine the USB hub market place is an extremely competitive one and every extra part in the unit lowers the profit made on each sale.