The PolynomialBase class has only three methods. One is the lazy property, which probably optimizes the access of param_names. The other two methods are __getattr__ and __setattr__. The code in the Model class [here](https://github.com/astropy/astropy/blob/master/astropy/modeling/core.py#L452) uses a few methods, that make it necessary for me to have [__getattr__](https://github.com/astropy/astropy/blob/master/astropy/modeling/polynomial.py#L62) and [__setattr__](https://github.com/astropy/astropy/blob/master/astropy/modeling/polynomial.py#L68) as defined in PolynomialBase. 
If I don't use this a a base class, then I will have to copy these methods in BSplineModel. Will that be okay?