Question: One standard approach to showing compactness of first-order logic is to show completeness, of which compactness is an easy corollary. I am told this approach is deprecated nowadays, as Compactness is seen as the "deeper" result. 

Could someone explain this intuition? In particular, are there logical systems which are compact but not complete?

EDIT: Andreas brings up an excellent point, which is that the Completeness theorem is really a combination of two very important but almost unrelated results. First, the Compactness theorem. Second, the recursive enumerability of logical validities. Note that neither of these results depends on the details on the syntactic or axiomatic system.

What is the connection between these two aspects of completeness? Are there logical systems that have one of these properties but not the other?

Answer: 
The point is that we care about the models, rather than about the proofs. The compactness theorem---the claim that a theory is satisfiable iff every finite subset of it is satisfiable---is fundamentally connected to the models, and the possiblility of truth in these models. To use it, you need to understand your theory, the models of your theory and the models of finite pieces of your theory. And this is what we want to be thinking about and what we know about. In particular, when working with models, we can use all the mathematical tools and constructions at our disposal, with no need to remain inside any first-order language or formal system (well, perhaps we have set theory as our background system). We are free to reason about the models via reducts and ultrapowers and limits of systems of morphisms and so on, using any mathematical method at all.

The completeness theorem, in contrast, is fundamentally connected with the details of a formal deduction system. And so when using it, one is thinking about whether certain tautologies might be provable or not, or whether a certain formal consequence is allowed in the system or not. 
But when we are studying a certain first-order class of groups or rings or whatever, such details about the proof system might seem to be an irrelevant distraction.
Here is an interesting quote from Bruno Poizat's "A Course in Model Theory":

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> The compactness theorem, in the forms of Theorems 4.5 and 4.6, is due to Gödel; in fact, as explained in the beginning of Section 4.3 [Henkin's Method], the theorem was for Gödel a simple corollary (we could even say an unexpected corollary, a rather strange remark!) of his "completeness theorem" of logic, in which he showed that a finite system of rules of inference is sufficient to express the notion of consequence (see Chapter 7). It could also have been taken from [Herbrand 1928] or [Gentzen 1934], in which results of the same sort were proven.
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> This unfortunate compactness theorem was brought in by the back door, and we might say that its original modesty still does it wrong in logic textbooks. In my opinion it is a much more essential and primordial (and thus also less sophisticated) than Gödel's completeness theorem, which states that we can formalize deduction in a certain arithmetic way; it is an error in method to deduce it from the latter.
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> If we do it this way, it is by a very blind fidelity to the historic conditions that witnessed its birth. The weight of this tradition is apparent even in a work like [Chang-Keisler 1973], which was considered a bible of model theory in the 1970s; it begins with syntactic developments that have nothing to do with anything in the succeeding chapters. This approach---deducing Compactness from the possibility of axiomatizing the notion of deduction---once applied to the propositional calculus gives the strangest proof on record of the compactness of $2^\omega$!
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> It is undoubtedly more "logical," but it is inconvenient, to require the student to absorb a system of formal deduction, ultimately quite arbitrary, which can be justified only much later when we can show that it indeed represents the notion of semantic consequence. We should not lose sight of the fact that the formalisms have no raison d'être except insofar as they are adequate for representing notions of substance.
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See also this [old answer of mine](https://mathoverflow.net/questions/9309/in-model-theory-does-compactness-easily-imply-completeness/11014#11014) where the same quote appears.