Well, first off, we'd need to come up with something better.

Just off the top of my head, let's say we use days as our main unit of time and then something like centi- and milli-days (and portions of milli-days) for shorter units. A centi-day is about 14 and a half minutes. A milli-day is 86.4 seconds.

But, then, so many of our other units are defined in terms of seconds. If we abandoned seconds, we'd have to come up with new units for energy, power, and any other units which are defined in terms of seconds.

So, in order to abandon seconds, we'd have to throw away the rest of the metric system and start over.

And, I suppose that's something we could do, but is it worth it?

And even if we did all that work, that wouldn't fix the fact that the time it takes to orbit the sun isn't a multiple of the amount of time a it takes the planet to revolve around its axis.

That said, there are definitely improvements we could make without wrecking the whole metric system. Daylight saving's time is ridiculously unpopular and you'd think we'd've gotten rid of it by now. I also think getting rid of time zones would be beneficial. Perhaps making all but one month the same length.