Your explanation is much better than your original post, thanks. Hierarchy (or nested) is a specific term used to designate a specific relationship between components of variation or factors. Hierarchy implies there is a rational order that must be accounted for. For example Batch-to-batch and within batch. Within batch must be nested within batch...you can't get multiple batches from a within batch sample.
Here are my thoughts:
Regarding "Hierarchical regression is a way to show if variables of your interest explain a statistically significant amount of variance in your Dependent Variable (DV) after accounting for all other variables."
1. Statistical significance is a conditional statement. It is dependent on inference space, and what components are being compared. It is completely dependent on how the data was collected. I'm not exactly sure what you mean by "after accounting for all other variables"? Analysis using type III SS will evaluate each term in your model after all of the other terms in your model are accounted for, but I don't think that is what you mean...
2. Context is always necessary to Interpret the analysis done by the software. Context must be provided by the topic "experts".
3. Designing a data collection plan that is driven by hypotheses and subsequently includes the sources of variation representative of those hypotheses is something you do...not the software. How you choose to subset those sources and what comparisons you want to make is your decision. Whether those sources are nested, systematic or crossed is a function of how you collect the data.
4. Rsq's are only one of the metrics used to develop models. I would not restrict the model building to that one value and I would use Rsq adjusted as default. Consider the delta between Rsq and Rsq adjusted (for over specifying the model), RMSE, p-values, residuals and residual plots, et. al.
5. "In this framework, you build several regression models by adding variables to a previous model at each step; later models always include smaller models in previous steps." This is essentially stepwise regression. You can choose the components to start with and what components to add or you can let the software evaluate this based on criteria you set.
https://www.jmp.com/support/help/en/16.2/?os=mac&source=application&utm_source=helpmenu&utm_medium=a...
You may also use partitioning platforms to perform similar functions.
https://www.jmp.com/support/help/en/16.2/?os=mac&source=application&utm_source=helpmenu&utm_medium=a...
Another option in JMP is to compare models:
https://www.jmp.com/support/help/en/16.2/?os=mac&source=application&utm_source=helpmenu&utm_medium=a...
6. "It's easy to do in SPSS, and I am a little disappointed that JMP doesn't offer a similar way to sequentially create blocks of variable." I don't use SPSS, but if you could show us what you mean, we might be able to guide you. What do you mean that the software sequentially creates blocks? You enter hypotheses into SPSS and it properly creates blocks for you? I'd like to see that.
7. Aggressive behavior measure = (age, gender) + (education, income) + (TV violence exposure). There are many more variables you have not included or are confounded with your model. Demographics, family unit, personal trauma, upbringing, exposure to real violence. And how do you measure aggressive behavior? Is your measurement system consistent? Does you measurement system bias the results?
"All models are wrong, some are useful" G.E.P. Box