My view is that the large cardinal hierarchy already has all the principal features of the project you are proposing. Each of the large cardinal concepts can be regarded as corresponding to a certain conception of the set-theoretic universe, if one should entertain the von Neuman hierarchy up to such a cardinal, and this makes a perfectly good universe. Every inaccessible cardinal $\kappa$, for example, gives rise $V_\kappa$, a transitive model of ZFC and a Grothendieck universe in fact. Every Mahlo cardinal $\lambda$ is a limit of many inaccessible cardinals $\kappa\lt\lambda$, and the models $V_\kappa\subset V_\lambda$ have much the same relation as what you describe in your question. If $\lambda$ is Mahlo, then the smaller models $V_\kappa$ for inaccessible $\kappa\lt\lambda$, which are perfectly good set theoretic universes, each extend up to $V_\lambda$, a larger universe having what it thinks is a proper class of inaccessible cardinals (and hence also the Universe Axiom). Indeed, when $\lambda$ is Mahlo then the collection of inaccessible cardinals is not merely unbounded in $\lambda$, as you request, but also forms what is known as a stationary class in $\lambda$, meaning that it intersects nontrivially with every closed unbounded set. This seems to extend and refine the idea of your cofinal tallness. Similarly, every weakly compact cardinal is a stationary limit of Mahlo cardinals, and if $\delta$ is a measurable cardinal, then not only are the weakly compact cardinals below $\delta$ stationary in $\delta$, but they form a set of normal measure one, a much stronger notion. This reflection phenomenon is nearly universal in the large cardinal hierarchy, where properties of the larger large cardinals reflect down to robust classes of the smaller cardinals. The strong cardinals reflect in this way down to the measurable cardinals, and the Mitchell order carries this idea still further. Supercompactness reflects down to superstrongness. It is an intensely studied phenomenon. In this sense, the subject of large cardinal set theory is already undertaking your project. What we are studying is precisely how all the various large cardinals can be construed as smaller universes extending into larger ones. For the large cardinals that are axiomatized in terms of the existence of certain embeddings $j:V\to M$, this extension process proceeds in two ways: $M$ is larger than $V$ in the sense that $\ran(j)\subset M$, and $M$ is smaller than $V$ in the sense that $M\subset V$. It is the interplay and tension between these two sense that gives rise to much of the power of these axioms. I would say that this includes elements of algebra, broadly construed, if one regards the direct limits and large systems of large cardinal embeddings that arise in the theory as having an essentially algebraic aspect. Surely the extender embeddings concepts developed in the theory of canonical inner models exhibit a fundamentally algebraic character. And the subject is hugely involved with philosophical considerations, which guide the choice of new large cardinal axioms as well as motivate or attempting to explain why we should believe that they are consistent or true. One can say infinitely more about this.