Purpose of "cover" for EB/HEB's?

OK, I'm totally new to this and finding it fascinating. Other than retaining moisure is there an advantage I'm missing?

I.E., DH made some steller open EBuckets for our FL screened area. Our tomatoes are going nuts, we can almost WATCH them grow! We're monitoring the water level, but since we're heading into the daily rainy season here in FL, is there a disadvantage to Ietting the tops open to the elements?

Thanks in advance!

Normally with a Earthbox and most likely HEB's and Ebuckets, you would put a fertilizer strip on the surface that feeds the plants for their whole life cycle. It is quite a lot of fert so if the planters were not covered and it rained on the fert and potting mix, It would all dissolve and burn the plants roots beyond repair. That is one of the main reasons to cover those planters. If you keep the covers off, I would feed the plants with a water soluble fert like MiracleGro at posted intervals.

Thanks, Bob - that's what we're doing. :)