How can lower ohms mean a hotter coil at the same voltage? I know that is the case, since the power (watts) is higher on a 1.8ohm coil at 3.7v than on a 2.4ohm but it just sounds so counter intuitive, after all we use use no resistance wires or double up the coil's legs so they don't get so hot.
Lower resistance means more power can efficiently pass. Since a coil is not a demand divide (that is it has no control of power, the switch in the unit is the demand device) it is limited to what the switch supplies. If you have a resistance, that will regulate maximum current.
Think of electricity as a plumbing system for a fountain. The pipe size is your voltage, the pressure is your ampage, watts would be GPM of water. A watt is a watt no matter watt voltage it is supplied, just the same as a gallon of watter is a gallon of water no matter the pressure supplied. Ohmage would be the interaction of the interior pipe surface, changes in pipe size (just like how wires and all components have some resistance) or like a pierced disk to reduce water flow (this is what would be the Ohmage of your atty/cart) the higher the resistance the less it allows power to flow through. This is why heating coils are made up of such thin wire coiled the way bit is (if any coil wire touches other coil wire it won't heat up nearly as much). It simply means more power gets to the coil.
Electronic resistors work in the same principle, and the result is always heat... which is why ac-dc adaptors get warm.
Smaller batteries drop voltage quicker. A 350 math battery will start around 4.2v (li-ion... some us lipo which runs 3.4 when charged down to 2.8-2.9 at full healthy discharge and end around 3.2-3.4. A 2 ohm cart gives you a starting power of a little over 8w. Ending you can be down around 5w... and when Vaping that difference you can taste, smell, and see...this is why VV and low wattage devices came about. It improved everything. With vv you can use whatever Res you want but you are reliant upon the max amperage the switch will supply.
Mech switch units rely upon the resistance as a safety... if therw was no rwsistance you would have a battery short and thus heating (resistance increases with heat) till either a lead or wire burnt out or the battwry goes kaboom...