When you have a new home or a new garden - or both - one of your spare time jobs is to install things, assemble furniture, remove weeds, plant and water, etc. Usually you have a choice of really manually performing a tasks, e.g., using a regular screwdriver, or trying to simplify and speed up what you want to accomplish, e.g., using a power screwdriver. For most tasks you have the choice of using mostly already present tools or investing into new power tools or similar stuff. The questions are always, how much time and effort can I save, how often will I use the power tool again (and sometimes even: if I buy the tool, will my significant other actually do it instead of me)?
Often, the decision is to buy a tool and to be happy about the simplifications and the saved time. The actual problem is to select the right brand and version of tool.
When you are running database applications the situation is similar. There are many tasks that can be performed by a skilled person without tools or just with whatever the core software (OS, DBMS, JDK, etc.) offers. However, often an additional tool can help to save time and improve the quality of what needed to be done. Similar questions as above for the house and garden need to be answered, only thereafter it can become more confusing when shopping for the right tool [Did you happen to select a power screwdriver that was renamed/rebranded a couple times?]. IBM offers a wealth of tools, sometimes for every problem even two, ranging from application development over data life cycle management and data encryption to performance monitoring.
Going back to house and garden, I usually buy tools from the same brand/company because they have the same "look and feel", once I dealt with one tool, it's quicker to learn how to handle the next. BTW: That's the same principle behind the Optim suite of tools for Integrated Data Management.