No, radioactive means they emit radiation - not that it's harmfull.Radioctive means they emit harmful radiation that poisons people and the environment; it's a problem by definition.
Harmfull depends on several factors.
What kind or radiation (alpha=not a big problem, beta worse, gamma generally bad)
How radioactive, things with a very long half life (eg. Pu) decay slowly and so only emit very small amounts of radiation. Things with a very short half life (eg. H3) emit a lot of radiation for a brief time but then become harmless quickly.
The bad ones are the half lives similair to a human lifespan.
It's chemical activity. Insoluble Pu or U in granite not a big problem. Radon that you can breathe into your lungs = bad, ceasium/iodine that build up in your body = worse.
Only if they are harmfull.They are a "problem" because they contaminate the soil and water, and are a danger to people and animals.
It's better than other pollutants, mercury and arsenic are still going to be as toxic at the end of the universe. The radioactive waste is getting safer all the time.Also it's not just like you can dump it somewhere and forget about it. Disposal sites must be monitered and protected and secured. Yet the waste can stay active for tens of thousands of years..
The waste problem is made worse by not reprocessing the most active (and therefore the most dangerous but also the most valuable components) for political reasons. But at least the waste is contained and stored. Try removing all the polution and CO2 produced by a coal power station form the atmosphere and storing it until it's no longer harmfull.