The roots do eventually grow through the straw, but the straw really helps to keep the soil at root level moist, so the roots will keep growing down for water instead of the roots reaching outward in shallow soil. It is just an easier way for me to water without wasting water and getting the water down to the root zone when the plants get bigger instead of trying to get the water to soak down to the roots. And without getting the leaves drenched all the time with the hard water that comes out of the spigot.
On another gardening forum I belonged to years ago, I saw some rather inventive setups for drip watering pots. But it involved having sets of the same pots at the same size. For instance a row of 20 or so tomato plants all in 10 gallon buckets next to rows of peppers in 5 gallon buckets. I personally think it would be easier to use those spike or soda bottle irrigation for pots to auto-water. I've done that with huge pots, but with smaller pots, I just find it easier to hand water so I can check which plants need water or other needs. I have a tendency to move pots around so that would be a problem with any system to water them automatically.
