Thats fine, I do like the simpicity of the loan system currently but had to ask the question.

We have considered this design option before but decided that it is better to keep the bank loan system simple. In fact, it is an on-going balancing act between game simplicity and the level of detail of the simulation throughout the development process.

Is it possible to consider fixed rate loans. for example if I take out a loan at my bank tomorrow, I will borrow at an agreed interest rate and a fixed time. IE borrow £5,000 at 5% over 5 years. At the moment your subject to whatever interest rate the central bank sets. I don't beleive this is very accurate. I don't belive that this should be removed but the game should have fixed rate too, it would give a better balance to the game and allow you to borrow money when the rates are low, to perhaps pay off a loan that was taken out at a higher rate. At the moment it's just pays the interest on the loan. Yes you can pay off the loan but surely you should be able to get a loan option which you can pay off a loan an agreed time. These loans could be set to a higher rate than current central bank rates but least it gives you some more loan options.
I do like the current interest only loan but I would like another option as I believe that you get this option in the real world. Credit ratings and penalties could then be considered but thats for another post.