These problems are only "uninteresting" to the extent that they can be "proven" by automated computation. So the interesting part of the problem is to write some completely formalized equivalent to a CAS (computer algebra system - think Mathematica or Maple, although these are not at all free from errors or bugs!) that might be able to dispatch these questions easily. Formalization systems can already simplify expressions in rings or fields (i.e. do routine school-level algebra), and answering some of these questions about limits or asymptotics is roughly comparable.
The problems are uninteresting in the sense that the audience for these papers doesn't find them interesting.
In particular, I'm not making any sort of logical claim -- rather, I know many of the people who read and write these papers, and I have a pretty good idea of their taste in mathematical writing.
Well, you did claim that the problem could be worked out with simply high school math. It would certainly be 'interesting' if such problems could not be answered by automated means.
(For example, I think many mathematicians would find the IMO problems interesting, even though the statements are specifically chosen to be understandable to high-school students.) The problem of how to write an automated procedure that might answer problems similar to the one you stated, and what kinds of "hints" might then be needed to make the procedure work for any given instance of the problem, is also interesting for similar reasons.
>> log(x^2 + 1) + sqrt(x) + x/exp(sqrt(4x + 3)) < Cx.
These problems are only "uninteresting" to the extent that they can be "proven" by automated computation. So the interesting part of the problem is to write some completely formalized equivalent to a CAS (computer algebra system - think Mathematica or Maple, although these are not at all free from errors or bugs!) that might be able to dispatch these questions easily. Formalization systems can already simplify expressions in rings or fields (i.e. do routine school-level algebra), and answering some of these questions about limits or asymptotics is roughly comparable.